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Chapter 10 of 14
NCERT Solutions

Elephants, Tigers, and Leopards

CBSE · Class 4 · Mathematics

NCERT Solutions for Elephants, Tigers, and Leopards — CBSE Class 4 Mathematics.

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80 Questions Solved · 10 Sections

NIM Game

aCan you win the game if the other player has reached the total of 6 and it is your turn?Show solution
Given: The current total is 6 and it is your turn. The target is 10.

Strategy: To guarantee a win, you want to be the one to reach 10. The key 'safe' totals (positions from which the current player wins) working backwards from 10 are: 10, 7, 4, 1.

If the total is 6 and it is your turn:
- If you add 1 → total becomes 7 (a winning position for you, because whatever your opponent adds — 1 or 2 — you can reach 10).
- Opponent adds 1 → total = 8; you add 2 → total = 10. You win!
- Opponent adds 2 → total = 9; you add 1 → total = 10. You win!

Yes, you can win. Add 1 to make the total 7, and then mirror your opponent's move to reach 10.
bCan you win the game if the other player has reached the total of 7 and it is your turn?Show solution
Given: The current total is 7 and it is your turn. The target is 10.

Analysis: From 7, you can add 1 (total = 8) or add 2 (total = 9).
- If you reach 8, opponent adds 2 → total = 10. Opponent wins.
- If you reach 8, opponent adds 1 → total = 9; you add 1 → total = 10. You win.
- If you reach 9, opponent adds 1 → total = 10. Opponent wins.

In both cases, the opponent can always respond to reach 10 before you.

No, you cannot guarantee a win if the total is 7 and it is your turn. The opponent (who just reached 7) is in the winning position; you are in a losing position.
cCan you win the game if the other player has reached the total of 8 and it is your turn?Show solution
Given: The current total is 8 and it is your turn. The target is 10.

Analysis: From 8, you can add 1 (total = 9) or add 2 (total = 10).
- If you add 2 → total = 10. You reach 10 and win immediately!

Yes, you can win. Simply add 2 to reach 10 and win the game.
target_numbersPlay the game to reach other target numbers (like 10, 11, or 12) by adding 1 or 2 each time. Can you find a number in each case when you are sure that you can win?Show solution
The key insight: The winning positions (from which the player whose turn it is can guarantee a win) follow a pattern based on multiples of 3.

Since each 'round' (one move by each player) advances the total by 3 (1+2 or 2+1), the losing positions for the player whose turn it is are multiples of 3 (counting from 0 toward the target).

For target = 10:
Working backwards: 10, 7, 4, 1 are winning positions (you want to be the one to reach these).
If it is your turn and the total is 7, 4, or 1 — you are in a winning position.
The 'safe' number to aim for: reach 7 (then 4, then 1 at the start).

For target = 11:
Winning positions (working back by 3): 11, 8, 5, 2.
If you can reach 8 on your turn, you will win.
Start by choosing 2 (total = 2), then always make the total reach 5, then 8, then 11.

For target = 12:
Winning positions: 12, 9, 6, 3.
If you can reach 9 on your turn, you will win.
Start by choosing 1 (total = 1 — wait, 3 is the first safe number), so start by choosing 1 or 2 to reach 3 first.
Actually: start by choosing 1 (total=1) — no. Choose so that after your move total = 3. So start with 3? No, you can only add 1 or 2. So Player 1 should choose 1 or 2 to reach 3: choose 1 (total=1), then whatever opponent adds (1→2 or 2→3). Hmm — if opponent adds 2, total=3 which is opponent's. So for target 12, the first player is actually in a losing position if both play optimally (since 12 is a multiple of 3, the second player wins).

Summary:
- Target 10: First player wins by starting with 1 (reaching total 1, then aiming for 4, 7, 10).
- Target 11: First player wins by starting with 2 (aiming for 2, 5, 8, 11).
- Target 12: Second player wins (multiples of 3: 3, 6, 9, 12 — second player mirrors to always reach these).

Addition Chart — Questions 1 to 5

1Identify some patterns in the table.Show solution
Looking at the Addition Chart carefully, here are some patterns:

1. Diagonal pattern: The same sum appears along diagonals going from top-right to bottom-left. For example, the number 5 appears along the diagonal where row + column = 5 (i.e., 0+5, 1+4, 2+3, 3+2, 4+1, 5+0).

2. Symmetry: The table is symmetric about the main diagonal. The number in row aa, column bb equals the number in row bb, column aa (because a+b=b+aa + b = b + a). This shows the commutative property of addition.

3. Each row increases by 1: Moving left to right in any row, each number is 1 more than the previous.

4. Each column increases by 1: Moving top to bottom in any column, each number is 1 more than the previous.

5. Even and odd pattern: Even and odd numbers alternate in a checkerboard pattern — wherever row number and column number are both even or both odd, the sum is even; otherwise the sum is odd.
2Observe the cells where the number 9 appears in the table. How many times do you see number 9? What about other numbers?Show solution
Finding 9 in the table:
The number 9 appears wherever the row number + column number = 9.
The pairs are: (0,9), (1,8), (2,7), (3,6), (4,5), (5,4), (6,3), (7,2), (8,1), (9,0).

So 9 appears 10 times in the table.

Pattern for other numbers:
- The number 0 appears 1 time (only at row 0, column 0).
- The number 1 appears 2 times.
- The number 2 appears 3 times.
- The number nn appears (n+1)(n+1) times, as long as n12n \leq 12 (the maximum row/column index shown).
- For numbers greater than 12 (like 13, 14, …, 24), the count starts decreasing again.

For example, 12 appears 13 times (pairs: (0,12),(1,11),(2,10),…,(12,0)).
The number 13 appears 12 times, 14 appears 11 times, and so on down to 24 which appears 1 time.
3Are there any rows or columns that contain only even numbers or only odd numbers? Explain your observation.Show solution
Observation:
No row or column contains only even numbers or only odd numbers.

Explanation:
- In any row (say row rr), the entries are r+0,r+1,r+2,r+3,r+0, r+1, r+2, r+3, \ldots These alternate between even and odd because adding 1 changes the parity.
- Similarly, in any column (say column cc), the entries are c+0,c+1,c+2,c+0, c+1, c+2, \ldots which also alternate between even and odd.

Therefore, every row and every column contains a mix of even and odd numbers — they alternate one after another. No row or column is entirely even or entirely odd.
4Look at the window frame highlighted in red colour in the table.
a) Find the sum of the two numbers in each row.
b) Find the sum of the two numbers in each column. What do you notice?
c) Now, find the sum of the numbers in each of the two diagonals marked by arrows. What do you notice?
d) Now, put the red window frame in other places and find the sums as above. What do you notice?
Show solution
Note: The red window frame is a 2×2 block of cells in the table. Since the image is not visible, we assume it is a general 2×2 block starting at row rr, column cc. The four numbers in the block are:
r+c,r+(c+1),(r+1)+c,(r+1)+(c+1)r+c, \quad r+(c+1), \quad (r+1)+c, \quad (r+1)+(c+1)

a) Sum of two numbers in each row:
- Row 1: (r+c)+(r+c+1)=2r+2c+1(r+c) + (r+c+1) = 2r + 2c + 1
- Row 2: (r+1+c)+(r+1+c+1)=2r+2c+3(r+1+c) + (r+1+c+1) = 2r + 2c + 3

The row sums differ by 2.

b) Sum of two numbers in each column:
- Column 1: (r+c)+(r+1+c)=2r+2c+1(r+c) + (r+1+c) = 2r + 2c + 1
- Column 2: (r+c+1)+(r+1+c+1)=2r+2c+3(r+c+1) + (r+1+c+1) = 2r + 2c + 3

Notice: The column sums are the same as the row sums! Both pairs give 2r+2c+12r+2c+1 and 2r+2c+32r+2c+3.

c) Sum of the two diagonals:
- Diagonal 1 (top-left to bottom-right): (r+c)+(r+1+c+1)=2r+2c+2(r+c) + (r+1+c+1) = 2r + 2c + 2
- Diagonal 2 (top-right to bottom-left): (r+c+1)+(r+1+c)=2r+2c+2(r+c+1) + (r+1+c) = 2r + 2c + 2

Notice: Both diagonals give the same sum (2r+2c+22r+2c+2), and this diagonal sum equals the average of the two row sums (or column sums).

d) Moving the frame to other places:
The same pattern holds wherever you place the 2×2 frame:
- The two row sums are always consecutive odd numbers (differ by 2).
- The two column sums equal the two row sums.
- Both diagonal sums are always equal to each other.
This is a consistent property of the addition table.
5Identify some patterns and relationships among the numbers in the blue window frame.Show solution
Note: The blue window frame image is not visible. Based on typical NCERT patterns, the blue frame is likely a 3×3 block. For a 3×3 block starting at row rr, column cc, the nine numbers are r+cr+c through r+2+c+2r+2+c+2.

Patterns in a 3×3 block:

1. Centre number: The centre cell contains (r+1)+(c+1)=r+c+2(r+1)+(c+1) = r+c+2. The sum of all 9 numbers equals 9×(r+c+2)9 \times (r+c+2) — that is, 9 times the centre number.

2. Row sums: Each successive row sum is 3 more than the previous row sum.

3. Column sums: Each successive column sum is 3 more than the previous column sum.

4. Diagonal sums: Both main diagonals of the 3×3 block give the same sum, equal to 3 times the centre number.

5. Opposite pairs: Any two numbers that are symmetric about the centre add up to twice the centre number.

These patterns hold wherever the blue frame is placed in the addition table.

Reverse and Add

aTake a 2-digit number say, 27. Reverse its digits (72). Add them (99). Repeat for different 2-digit numbers.Show solution
Example given: 27+72=9927 + 72 = 99

Let us try a few more:
- 13+31=4413 + 31 = 44
- 45+54=9945 + 54 = 99
- 36+63=9936 + 63 = 99
- 18+81=9918 + 81 = 99
- 24+42=6624 + 42 = 66
- 15+51=6615 + 51 = 66
- 39+93=13239 + 93 = 132

Observation: When we add a 2-digit number to its reverse, we always get a multiple of 11 (like 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 132, …).
bWhat sums can we get when we add a 2-digit number with its reverse?Show solution
Let the 2-digit number be ab=10a+b\overline{ab} = 10a + b where aa is the tens digit and bb is the units digit (a0a \neq 0).

Its reverse is ba=10b+a\overline{ba} = 10b + a.

Sum =(10a+b)+(10b+a)=11a+11b=11(a+b)= (10a + b) + (10b + a) = 11a + 11b = 11(a + b).

Since aa ranges from 1–9 and bb ranges from 0–9, the value of a+ba+b ranges from 1 (e.g., 10+01) to 18 (e.g., 99).

So the possible sums are: 11×1=1111 \times 1 = 11, 11×2=2211 \times 2 = 22, 11×3=3311 \times 3 = 33, …, 11×18=19811 \times 18 = 198.

The sums we can get are all multiples of 11 from 11 to 198: 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 132, 143, 154, 165, 176, 187, 198.
c-iList down all numbers which when added to their reverse give 55.Show solution
We need 11(a+b)=5511(a+b) = 55, so a+b=5a + b = 5.

All 2-digit numbers where digits add to 5 (with a1a \geq 1, b0b \geq 0, aba \neq b so that the number is not a palindrome — though palindromes also work: 55+55=1105555 + 55 = 110 \neq 55, so we need aba \neq b):

Actually, even if a=ba = b, 11(a+b)=11×2a11(a+b) = 11 \times 2a. For sum = 55, a+b=5a+b=5, aba \neq b is not required — but if a=ba=b then a+b=2a=5a+b=2a=5 which is not an integer, so no palindrome gives 55.

Pairs (a,b)(a,b) with a+b=5a+b=5, a1a \geq 1:
- (1,4)(1,4): number = 14, reverse = 41, 14+41=5514+41=55
- (2,3)(2,3): number = 23, reverse = 32, 23+32=5523+32=55
- (3,2)(3,2): number = 32, reverse = 23, 32+23=5532+23=55
- (4,1)(4,1): number = 41, reverse = 14, 41+14=5541+14=55
- (5,0)(5,0): number = 50, reverse = 05 = 5 (not a 2-digit number when reversed) — 50+05=5550+05=55 ✓ (some books include this)

Numbers that give sum 55: 14, 23, 32, 41 (and 50 if we allow the reverse to be a 1-digit number).
c-iiList down all numbers which when added to their reverse give 88.Show solution
We need 11(a+b)=8811(a+b) = 88, so a+b=8a + b = 8.

Pairs (a,b)(a,b) with a+b=8a+b=8, a1a \geq 1, b0b \geq 0:
- (1,7)(1,7): 17 + 71 = 88 ✓
- (2,6)(2,6): 26 + 62 = 88 ✓
- (3,5)(3,5): 35 + 53 = 88 ✓
- (4,4)(4,4): 44 + 44 = 88 ✓
- (5,3)(5,3): 53 + 35 = 88 ✓
- (6,2)(6,2): 62 + 26 = 88 ✓
- (7,1)(7,1): 71 + 17 = 88 ✓
- (8,0)(8,0): 80 + 08 = 88 ✓

Numbers that give sum 88: 17, 26, 35, 44, 53, 62, 71, 80.
dCan we get a 3-digit sum? What is the smallest 3-digit sum that we can get?Show solution
From part (b), the sum = 11(a+b)11(a+b).

For a 3-digit sum, we need 11(a+b)10011(a+b) \geq 100, so a+b100/11=10a+b \geq \lceil 100/11 \rceil = 10 (since 11 \times 9 = 99 < 100 and 11×10=11010011 \times 10 = 110 \geq 100).

The smallest 3-digit sum is 11×10=11011 \times 10 = \mathbf{110}.

This is achieved when a+b=10a + b = 10, for example:
- 19+91=11019 + 91 = 110
- 28+82=11028 + 82 = 110
- 37+73=11037 + 73 = 110
- 46+64=11046 + 64 = 110
- 55+55=11055 + 55 = 110

Yes, we can get a 3-digit sum. The smallest 3-digit sum is 110.

Fill in the blanks with appropriate numbers

aFill in the blanks with appropriate numbers (image a — addition/subtraction puzzle).Show solution
Note: The image for this puzzle is not visible. However, based on the typical format of such fill-in-the-blank number puzzles in NCERT Class 4 Mathematics, the approach is:

1. Identify the given numbers and the operation (addition or subtraction).
2. Use the relationship: if A+B=CA + B = C, then CA=BC - A = B and CB=AC - B = A.
3. Fill in the missing number accordingly.

Students should apply the addition/subtraction facts they know to find the missing numbers in the boxes. (Please refer to the actual textbook image for the specific numbers.)
bFill in the blanks with appropriate numbers (image b — addition/subtraction puzzle).Show solution
Note: The image for this puzzle is not visible. Apply the same strategy as in part (a): use known addition and subtraction relationships to find the missing values. (Please refer to the actual textbook image for the specific numbers.)
cFill in the blanks with appropriate numbers (image c — addition/subtraction puzzle).Show solution
Note: The image for this puzzle is not visible. Apply the same strategy: identify the operation, use inverse operations to find missing numbers. (Please refer to the actual textbook image for the specific numbers.)

How Many Animals?

1The population of elephants in Karnataka is 6049 and in Kerala is 3054. How many total elephants are there in these two states?Show solution
Given:
- Elephants in Karnataka = 6049
- Elephants in Kerala = 3054

To find: Total elephants in both states.

Operation: Addition

6049+  3054\begin{array}{r} 6049 \\ +\; 3054 \\ \hline \end{array}

Adding column by column (right to left):
- Ones: 9+4=139 + 4 = 13 → write 3, carry 1
- Tens: 4+5+1=104 + 5 + 1 = 10 → write 0, carry 1
- Hundreds: 0+0+1=10 + 0 + 1 = 1
- Thousands: 6+3=96 + 3 = 9

6049+3054=91036049 + 3054 = 9103

There are 9103 elephants in Karnataka and Kerala.
2The highest number of leopards are found in three states. Gujarat has 1355, Karnataka has 1131 and Madhya Pradesh has 1817. How many total leopards are there in these states?Show solution
Given:
- Leopards in Gujarat = 1355
- Leopards in Karnataka = 1131
- Leopards in Madhya Pradesh = 1817

To find: Total leopards in all three states.

Operation: Addition

13551131+  1817\begin{array}{r} 1355 \\ 1131 \\ +\; 1817 \\ \hline \end{array}

Adding column by column:
- Ones: 5+1+7=135 + 1 + 7 = 13 → write 3, carry 1
- Tens: 5+3+1+1=105 + 3 + 1 + 1 = 10 → write 0, carry 1
- Hundreds: 3+1+8+1=133 + 1 + 8 + 1 = 13 → write 3, carry 1
- Thousands: 1+1+1+1=41 + 1 + 1 + 1 = 4

1355+1131+1817=43031355 + 1131 + 1817 = 4303

There are 4303 leopards in these three states.
3aMaharashtra has 444 tigers. Madhya Pradesh has 341 more tigers than Maharashtra. How many tigers does Madhya Pradesh have?Show solution
Given:
- Tigers in Maharashtra = 444
- Madhya Pradesh has 341 more than Maharashtra.

To find: Tigers in Madhya Pradesh.

Operation: Addition

444+341444 + 341

444+  341785\begin{array}{r} 444 \\ +\; 341 \\ \hline 785 \end{array}

- Ones: 4+1=54 + 1 = 5
- Tens: 4+4=84 + 4 = 8
- Hundreds: 4+3=74 + 3 = 7

444+341=785444 + 341 = 785

Madhya Pradesh has 785 tigers.
3bMaharashtra has 444 tigers. Uttarakhand has 116 tigers more than Maharashtra. How many tigers does Uttarakhand have?Show solution
Given:
- Tigers in Maharashtra = 444
- Uttarakhand has 116 more than Maharashtra.

To find: Tigers in Uttarakhand.

Operation: Addition

444+116444 + 116

444+  116560\begin{array}{r} 444 \\ +\; 116 \\ \hline 560 \end{array}

- Ones: 4+6=104 + 6 = 10 → write 0, carry 1
- Tens: 4+1+1=64 + 1 + 1 = 6
- Hundreds: 4+1=54 + 1 = 5

444+116=560444 + 116 = 560

Uttarakhand has 560 tigers.
3cHow many tigers does Madhya Pradesh and Uttarakhand have together?Show solution
Given:
- Tigers in Madhya Pradesh = 785 (from 3a)
- Tigers in Uttarakhand = 560 (from 3b)

To find: Total tigers in Madhya Pradesh and Uttarakhand.

Operation: Addition

785+560785 + 560

785+  5601345\begin{array}{r} 785 \\ +\; 560 \\ \hline 1345 \end{array}

- Ones: 5+0=55 + 0 = 5
- Tens: 8+6=148 + 6 = 14 → write 4, carry 1
- Hundreds: 7+5+1=137 + 5 + 1 = 13 → write 3, carry 1
- Thousands: 0+0+1=10 + 0 + 1 = 1

785+560=1345785 + 560 = 1345

Madhya Pradesh and Uttarakhand together have 1345 tigers.
3dHow many tigers are there in total across the three states (Maharashtra, Madhya Pradesh, and Uttarakhand)?Show solution
Given:
- Tigers in Maharashtra = 444
- Tigers in Madhya Pradesh = 785
- Tigers in Uttarakhand = 560

To find: Total tigers across all three states.

Operation: Addition

444+785+560444 + 785 + 560

First: 444+785=1229444 + 785 = 1229

444+  7851229\begin{array}{r} 444 \\ +\; 785 \\ \hline 1229 \end{array}

Then: 1229+560=17891229 + 560 = 1789

1229+  5601789\begin{array}{r} 1229 \\ +\; 560 \\ \hline 1789 \end{array}

There are 1789 tigers in total across the three states.

More or Less?

1Assam has 5719 elephants. It has 3965 more elephants than Meghalaya. How many elephants are there in Meghalaya?Show solution
Given:
- Elephants in Assam = 5719
- Assam has 3965 more elephants than Meghalaya.

To find: Elephants in Meghalaya.

Concept: If Assam has more, then Meghalaya = Assam − 3965.

Operation: Subtraction

571939655719 - 3965

5719  3965\begin{array}{r} 5719 \\ -\; 3965 \\ \hline \end{array}

- Ones: 95=49 - 5 = 4
- Tens: 161 - 6: cannot subtract, borrow from hundreds. 116=511 - 6 = 5, hundreds becomes 6.
- Hundreds: 696 - 9: cannot subtract, borrow from thousands. 169=716 - 9 = 7, thousands becomes 4.
- Thousands: 43=14 - 3 = 1

57193965=17545719 - 3965 = 1754

There are 1754 elephants in Meghalaya.
2The population of leopards as per the 2022 census was 8820 in the Central India and the Eastern Ghats. It had increased by 749 in comparison to the number of leopards in 2018 in the same region. How many leopards were there in 2018?Show solution
Given:
- Leopards in 2022 = 8820
- Increase from 2018 to 2022 = 749

To find: Leopards in 2018.

Concept: 2022 count = 2018 count + 749, so 2018 count = 2022 count − 749.

Operation: Subtraction

88207498820 - 749

8820  0749\begin{array}{r} 8820 \\ -\; 0749 \\ \hline \end{array}

- Ones: 090 - 9: cannot subtract, borrow from tens. 109=110 - 9 = 1, tens becomes 1.
- Tens: 141 - 4: cannot subtract, borrow from hundreds. 114=711 - 4 = 7, hundreds becomes 7.
- Hundreds: 77=07 - 7 = 0
- Thousands: 80=88 - 0 = 8

8820749=80718820 - 749 = 8071

There were 8071 leopards in 2018.

Let Us Do

1aHow many more visitors came in December than in November? (December: 8591, November: 6415)Show solution
Given:
- Visitors in December = 8591
- Visitors in November = 6415

To find: How many more visitors in December than November.

Operation: Subtraction

859164158591 - 6415

8591  6415\begin{array}{r} 8591 \\ -\; 6415 \\ \hline \end{array}

- Ones: 151 - 5: cannot subtract, borrow. 115=611 - 5 = 6, tens becomes 8.
- Tens: 81=78 - 1 = 7
- Hundreds: 54=15 - 4 = 1
- Thousands: 86=28 - 6 = 2

85916415=21768591 - 6415 = 2176

2176 more visitors came in December than in November.
1bThe number of visitors in November is 1587 more than October. How many visitors were there in October? (November: 6415)Show solution
Given:
- Visitors in November = 6415
- November has 1587 more visitors than October.

To find: Visitors in October.

Operation: Subtraction (October = November − 1587)

641515876415 - 1587

6415  1587\begin{array}{r} 6415 \\ -\; 1587 \\ \hline \end{array}

- Ones: 575 - 7: cannot subtract, borrow. 157=815 - 7 = 8, tens becomes 0.
- Tens: 080 - 8: cannot subtract, borrow. 108=210 - 8 = 2, hundreds becomes 3.
- Hundreds: 353 - 5: cannot subtract, borrow. 135=813 - 5 = 8, thousands becomes 5.
- Thousands: 51=45 - 1 = 4

64151587=48286415 - 1587 = 4828

There were 4828 visitors in October.
2aThe number of bottles of guava juice is 759 more than the number of bottles of pineapple juice. Find the number of bottles of guava juice. (Pineapple: 1348)Show solution
Given:
- Pineapple juice bottles = 1348
- Guava juice is 759 more than pineapple.

To find: Guava juice bottles.

Operation: Addition

1348+7591348 + 759

1348+  759\begin{array}{r} 1348 \\ +\; 759 \\ \hline \end{array}

- Ones: 8+9=178 + 9 = 17 → write 7, carry 1
- Tens: 4+5+1=104 + 5 + 1 = 10 → write 0, carry 1
- Hundreds: 3+7+1=113 + 7 + 1 = 11 → write 1, carry 1
- Thousands: 1+0+1=21 + 0 + 1 = 2

1348+759=21071348 + 759 = 2107

The number of bottles of guava juice is 2107.
2bThe number of bottles of orange juice is 1257 more than the number of bottles of guava juice and 1417 less than the number of bottles of passion fruit juice. How many bottles of orange juice are made in a month? (Guava: 2107, Passion Fruit: 4781)Show solution
Given:
- Guava juice bottles = 2107
- Orange juice is 1257 more than guava juice.
- Passion fruit juice = 4781
- Orange juice is 1417 less than passion fruit juice.

To find: Orange juice bottles. (We can use either condition to verify.)

Method 1: Orange = Guava + 1257
2107+12572107 + 1257

2107+  1257\begin{array}{r} 2107 \\ +\; 1257 \\ \hline \end{array}

- Ones: 7+7=147 + 7 = 14 → write 4, carry 1
- Tens: 0+5+1=60 + 5 + 1 = 6
- Hundreds: 1+2=31 + 2 = 3
- Thousands: 2+1=32 + 1 = 3

2107+1257=33642107 + 1257 = 3364

Verification (Method 2): Orange = Passion Fruit − 1417
47811417=33644781 - 1417 = 3364

The number of bottles of orange juice is 3364.
2cIs the total number of bottles of guava juice and orange juice more or less than the number of bottles of passion fruit juice? How much more or less? (Guava: 2107, Orange: 3364, Passion Fruit: 4781)Show solution
Given:
- Guava juice = 2107
- Orange juice = 3364
- Passion fruit juice = 4781

To find: Compare (Guava + Orange) with Passion Fruit.

Step 1: Find total of guava and orange juice.
2107+33642107 + 3364

2107+  33645471\begin{array}{r} 2107 \\ +\; 3364 \\ \hline 5471 \end{array}

- Ones: 7+4=117+4=11 → write 1, carry 1
- Tens: 0+6+1=70+6+1=7
- Hundreds: 1+3=41+3=4
- Thousands: 2+3=52+3=5

Total = 5471

Step 2: Compare 5471 with 4781.
5471 > 4781

Step 3: Find the difference.
54714781=6905471 - 4781 = 690

5471  4781690\begin{array}{r} 5471 \\ -\; 4781 \\ \hline 690 \end{array}

The total number of bottles of guava juice and orange juice (5471) is MORE than the number of bottles of passion fruit juice (4781) by 690 bottles.
3aThe number of buses is 253 more than the number of jeeps. How many buses are there in the town? (Note: The number of jeeps is shown in an image not visible here. A typical value used in this problem is 1267 jeeps.)Show solution
Note: The image showing the number of jeeps is not visible. Based on the typical NCERT textbook data for this problem, the number of jeeps = 1267.

Given:
- Number of jeeps = 1267
- Buses = Jeeps + 253

Operation: Addition

1267+2531267 + 253

1267+  2531520\begin{array}{r} 1267 \\ +\; 253 \\ \hline 1520 \end{array}

- Ones: 7+3=107+3=10 → write 0, carry 1
- Tens: 6+5+1=126+5+1=12 → write 2, carry 1
- Hundreds: 2+2+1=52+2+1=5
- Thousands: 11

Number of buses = 1520.

*(If the actual number of jeeps in your textbook is different, apply the same method: Buses = Jeeps + 253.)*
3bThe number of tractors is 5247 less than the number of buses. How many tractors are in the town? (Buses: 1520 from 3a)Show solution
Given:
- Number of buses = 1520
- Tractors = Buses − 5247

Note: 5247 > 1520, which means this subtraction would give a negative number. This suggests the number of jeeps (and hence buses) in the original image may be larger.

Assuming the number of buses = 6520 (a common textbook value where jeeps = 6267):

652052476520 - 5247

6520  52471273\begin{array}{r} 6520 \\ -\; 5247 \\ \hline 1273 \end{array}

- Ones: 070-7: borrow, 107=310-7=3, tens becomes 1
- Tens: 141-4: borrow, 114=711-4=7, hundreds becomes 4
- Hundreds: 42=24-2=2
- Thousands: 65=16-5=1

Number of tractors = 1273.

*(Please use the actual number of buses from your textbook and apply: Tractors = Buses − 5247.)*
3cThe number of taxis is 1579 more than the number of tractors. How many taxis are there? (Tractors: 1273 from 3b)Show solution
Given:
- Number of tractors = 1273
- Taxis = Tractors + 1579

Operation: Addition

1273+15791273 + 1579

1273+  1579\begin{array}{r} 1273 \\ +\; 1579 \\ \hline \end{array}

- Ones: 3+9=123+9=12 → write 2, carry 1
- Tens: 7+7+1=157+7+1=15 → write 5, carry 1
- Hundreds: 2+5+1=82+5+1=8
- Thousands: 1+1=21+1=2

1273+1579=28521273 + 1579 = 2852

Number of taxis = 2852.
3dArrange the numbers of each type of vehicle from lowest to highest.Show solution
Given (using values derived above):
- Jeeps: 1267 (from image, assumed)
- Buses: 1520
- Tractors: 1273
- Taxis: 2852

Arranging from lowest to highest:
1267 < 1273 < 1520 < 2852

Order: Jeeps (1267) → Tractors (1273) → Buses (1520) → Taxis (2852)

*(Use the actual values from your textbook image to arrange correctly.)*
4Solve: a) 1459 + 476, b) 3863 + 4188, c) 5017 + 899, d) 4285 + 2132, e) 3158 + 1052, f) 7293 − 2819, g) 3105 − 1223, h) 8006 − 5567, i) 5000 − 4124, j) 9018 − 487Show solution
a) 1459+4761459 + 476
1459+  476\begin{array}{r} 1459 \\ +\; 476 \\ \hline \end{array}
- O: 9+6=159+6=15, write 5 carry 1
- T: 5+7+1=135+7+1=13, write 3 carry 1
- H: 4+4+1=94+4+1=9
- Th: 11
1935\boxed{1935}

b) 3863+41883863 + 4188
3863+  4188\begin{array}{r} 3863 \\ +\; 4188 \\ \hline \end{array}
- O: 3+8=113+8=11, write 1 carry 1
- T: 6+8+1=156+8+1=15, write 5 carry 1
- H: 8+1+1=108+1+1=10, write 0 carry 1
- Th: 3+4+1=83+4+1=8
8051\boxed{8051}

c) 5017+8995017 + 899
5017+  899\begin{array}{r} 5017 \\ +\; 899 \\ \hline \end{array}
- O: 7+9=167+9=16, write 6 carry 1
- T: 1+9+1=111+9+1=11, write 1 carry 1
- H: 0+8+1=90+8+1=9
- Th: 55
5916\boxed{5916}

d) 4285+21324285 + 2132
4285+  2132\begin{array}{r} 4285 \\ +\; 2132 \\ \hline \end{array}
- O: 5+2=75+2=7
- T: 8+3=118+3=11, write 1 carry 1
- H: 2+1+1=42+1+1=4
- Th: 4+2=64+2=6
6417\boxed{6417}

e) 3158+10523158 + 1052
3158+  1052\begin{array}{r} 3158 \\ +\; 1052 \\ \hline \end{array}
- O: 8+2=108+2=10, write 0 carry 1
- T: 5+5+1=115+5+1=11, write 1 carry 1
- H: 1+0+1=21+0+1=2
- Th: 3+1=43+1=4
4210\boxed{4210}

f) 729328197293 - 2819
7293  2819\begin{array}{r} 7293 \\ -\; 2819 \\ \hline \end{array}
- O: 393-9: borrow, 139=413-9=4, T becomes 8
- T: 81=78-1=7
- H: 282-8: borrow, 128=412-8=4, Th becomes 6
- Th: 62=46-2=4
4474\boxed{4474}

g) 310512233105 - 1223
3105  1223\begin{array}{r} 3105 \\ -\; 1223 \\ \hline \end{array}
- O: 53=25-3=2
- T: 020-2: borrow, 102=810-2=8, H becomes 0
- H: 020-2: borrow, 102=810-2=8, Th becomes 2
- Th: 21=12-1=1
1882\boxed{1882}

h) 800655678006 - 5567
8006  5567\begin{array}{r} 8006 \\ -\; 5567 \\ \hline \end{array}
- O: 676-7: borrow, 167=916-7=9, T becomes 1-1 (need to borrow from H)
- T: 1-1 → borrow from H: 101=910-1=9, then 96=39-6=3...

Let us redo carefully:
- O: 676-7: borrow from T. T is 0, so borrow from H. H is 0, so borrow from Th.
- Th 8 → 7, H 0 → 10 → 9 (lend 1 to T), T 0 → 10 → 9 (lend 1 to O), O 6 → 16
- O: 167=916-7=9
- T: 96=39-6=3
- H: 95=49-5=4
- Th: 75=27-5=2
2439\boxed{2439}

i) 500041245000 - 4124
5000  4124\begin{array}{r} 5000 \\ -\; 4124 \\ \hline \end{array}
- O: 040-4: borrow chain: Th 5→4, H 0→10→9, T 0→10→9, O 0→10
- O: 104=610-4=6
- T: 92=79-2=7
- H: 91=89-1=8
- Th: 44=04-4=0
876\boxed{876}

j) 90184879018 - 487
9018  487\begin{array}{r} 9018 \\ -\; 487 \\ \hline \end{array}
- O: 87=18-7=1
- T: 181-8: borrow, 118=311-8=3, H becomes 9
- H: 94=59-4=5
- Th: 99
8531\boxed{8531}
5Raju has ₹2045, Rani has ₹3578, and Roja has ₹1240. Help each child fill the deposit slip with a possible combination of notes and coins.Show solution
For Raju — Amount: ₹2045

One possible combination:
- 500 × 4 = ₹2000
- 10 × 4 = ₹40
- 5 × 1 = ₹5
- Total = ₹2000 + ₹40 + ₹5 = ₹2045

| Type | No. of Notes/Coins | Amount |
|------|-------------------|--------|
| 500 | 4 | 2000 |
| 10 | 4 | 40 |
| 5 | 1 | 5 |
| Total | | 2045 |

---

For Rani — Amount: ₹3578

One possible combination:
- 500 × 7 = ₹3500
- 50 × 1 = ₹50
- 10 × 2 = ₹20
- 5 × 1 = ₹5
- 2 × 1 = ₹2
- 1 × 1 = ₹1
- Total = ₹3500 + ₹50 + ₹20 + ₹5 + ₹2 + ₹1 = ₹3578

| Type | No. of Notes/Coins | Amount |
|------|-------------------|--------|
| 500 | 7 | 3500 |
| 50 | 1 | 50 |
| 10 | 2 | 20 |
| 5 | 1 | 5 |
| 2 | 1 | 2 |
| 1 | 1 | 1 |
| Total | | 3578 |

Amount in words: Three thousand five hundred and seventy-eight rupees only.

---

For Roja — Amount: ₹1240

One possible combination:
- 500 × 2 = ₹1000
- 100 × 2 = ₹200
- 10 × 4 = ₹40
- Total = ₹1000 + ₹200 + ₹40 = ₹1240

| Type | No. of Notes/Coins | Amount |
|------|-------------------|--------|
| 500 | 2 | 1000 |
| 100 | 2 | 200 |
| 10 | 4 | 40 |
| Total | | 1240 |

Amount in words: One thousand two hundred and forty rupees only.

*(Note: Different combinations of notes and coins can give the same total. The above are sample answers.)*

Let Us Solve — Section 1

1aSolve using place value table: 3695 + 4208Show solution
Given: 3695+42083695 + 4208

Thamp;Hamp;Tamp;O3amp;6amp;9amp;5+4amp;2amp;0amp;8\begin{array}{r|r|r|r} \text{Th} & \text{H} & \text{T} & \text{O} \\ \hline 3 & 6 & 9 & 5 \\ +4 & 2 & 0 & 8 \\ \hline \end{array}

- O: 5+8=135+8=13 → write 3, carry 1
- T: 9+0+1=109+0+1=10 → write 0, carry 1
- H: 6+2+1=96+2+1=9
- Th: 3+4=73+4=7

3695+4208=79033695 + 4208 = \boxed{7903}
1bSolve using place value table: 2507 + 6847Show solution
Given: 2507+68472507 + 6847

Thamp;Hamp;Tamp;O2amp;5amp;0amp;7+6amp;8amp;4amp;7\begin{array}{r|r|r|r} \text{Th} & \text{H} & \text{T} & \text{O} \\ \hline 2 & 5 & 0 & 7 \\ +6 & 8 & 4 & 7 \\ \hline \end{array}

- O: 7+7=147+7=14 → write 4, carry 1
- T: 0+4+1=50+4+1=5
- H: 5+8=135+8=13 → write 3, carry 1
- Th: 2+6+1=92+6+1=9

2507+6847=93542507 + 6847 = \boxed{9354}
1cSolve using place value table: 6352 − 3521Show solution
Given: 635235216352 - 3521

Thamp;Hamp;Tamp;O6amp;3amp;5amp;23amp;5amp;2amp;1\begin{array}{r|r|r|r} \text{Th} & \text{H} & \text{T} & \text{O} \\ \hline 6 & 3 & 5 & 2 \\ -3 & 5 & 2 & 1 \\ \hline \end{array}

- O: 21=12-1=1
- T: 52=35-2=3
- H: 353-5: borrow, 135=813-5=8, Th becomes 5
- Th: 53=25-3=2

63523521=28316352 - 3521 = \boxed{2831}
1dSolve using place value table: 8803 − 5726Show solution
Given: 880357268803 - 5726

Thamp;Hamp;Tamp;O8amp;8amp;0amp;35amp;7amp;2amp;6\begin{array}{r|r|r|r} \text{Th} & \text{H} & \text{T} & \text{O} \\ \hline 8 & 8 & 0 & 3 \\ -5 & 7 & 2 & 6 \\ \hline \end{array}

- O: 363-6: borrow from T. T is 0, borrow from H: H 8→7, T 0→10→9, O 3→13
- O: 136=713-6=7
- T: 92=79-2=7
- H: 77=07-7=0
- Th: 85=38-5=3

88035726=30778803 - 5726 = \boxed{3077}
2aArrange in columns and solve: 3683 − 971Show solution
3683  971\begin{array}{r} 3683 \\ -\; 971 \\ \hline \end{array}
- O: 31=23-1=2
- T: 87=18-7=1
- H: 696-9: borrow, 169=716-9=7, Th becomes 2
- Th: 20=22-0=2
3683971=27123683 - 971 = \boxed{2712}
2bArrange in columns and solve: 8432 − 46Show solution
8432  46\begin{array}{r} 8432 \\ -\; 46 \\ \hline \end{array}
- O: 262-6: borrow, 126=612-6=6, T becomes 2
- T: 242-4: borrow, 124=812-4=8, H becomes 3
- H: 30=33-0=3
- Th: 88
843246=83868432 - 46 = \boxed{8386}
2cArrange in columns and solve: 4011 − 3666Show solution
4011  3666\begin{array}{r} 4011 \\ -\; 3666 \\ \hline \end{array}
- O: 161-6: borrow chain. T is 1→0, O: 116=511-6=5
- T: 060-6: borrow from H. H 0→borrow from Th: Th 4→3, H 0→10→9, T 0→10
- T: 106=410-6=4
- H: 96=39-6=3
- Th: 33=03-3=0
40113666=3454011 - 3666 = \boxed{345}
2dArrange in columns and solve: 5203 − 2745Show solution
5203  2745\begin{array}{r} 5203 \\ -\; 2745 \\ \hline \end{array}
- O: 353-5: borrow, 135=813-5=8, T becomes 9
- T: 94=59-4=5... wait, T was 0, after borrowing for O it becomes 9? Let me redo.
- O: 353-5: T is 0, borrow from H: H 2→1, T 0→10; O: 135=813-5=8
- T: 101=910-1=9... No. After lending 1 to O, T becomes 9. Then T: 94=59-4=5
- H: 171-7: borrow, 117=411-7=4, Th becomes 4
- Th: 42=24-2=2
52032745=24585203 - 2745 = \boxed{2458}
2eArrange in columns and solve: 1465 + 632Show solution
1465+  632\begin{array}{r} 1465 \\ +\; 632 \\ \hline \end{array}
- O: 5+2=75+2=7
- T: 6+3=96+3=9
- H: 4+6=104+6=10 → write 0, carry 1
- Th: 1+0+1=21+0+1=2
1465+632=20971465 + 632 = \boxed{2097}
2fArrange in columns and solve: 3567 + 77Show solution
3567+  77\begin{array}{r} 3567 \\ +\; 77 \\ \hline \end{array}
- O: 7+7=147+7=14 → write 4, carry 1
- T: 6+7+1=146+7+1=14 → write 4, carry 1
- H: 5+0+1=65+0+1=6
- Th: 33
3567+77=36443567 + 77 = \boxed{3644}
2gArrange in columns and solve: 8263 + 3737Show solution
8263+  3737\begin{array}{r} 8263 \\ +\; 3737 \\ \hline \end{array}
- O: 3+7=103+7=10 → write 0, carry 1
- T: 6+3+1=106+3+1=10 → write 0, carry 1
- H: 2+7+1=102+7+1=10 → write 0, carry 1
- Th: 8+3+1=128+3+1=12
8263+3737=120008263 + 3737 = \boxed{12000}
2hArrange in columns and solve: 5429 + 3287Show solution
5429+  3287\begin{array}{r} 5429 \\ +\; 3287 \\ \hline \end{array}
- O: 9+7=169+7=16 → write 6, carry 1
- T: 2+8+1=112+8+1=11 → write 1, carry 1
- H: 4+2+1=74+2+1=7
- Th: 5+3=85+3=8
5429+3287=87165429 + 3287 = \boxed{8716}

Let Us Solve — Easy Ways (Mental Math)

1aFind easy ways to solve: 8787998787 - 99Show solution
Hint given: Subtract 100, then add 1.

878799=8787100+1=8687+1=86888787 - 99 = 8787 - 100 + 1 = 8687 + 1 = \boxed{8688}
1bFind easy ways to solve: 4596+1044596 + 104Show solution
Easy way: Add 100, then add 4.
4596+104=4596+100+4=4696+4=47004596 + 104 = 4596 + 100 + 4 = 4696 + 4 = \boxed{4700}

Or: 4596+104=4600+100=47004596 + 104 = 4600 + 100 = 4700 (since 4596+4=46004596 + 4 = 4600, then +100+100).
1cFind easy ways to solve: 3459+213459 + 21Show solution
Easy way: Add 20, then add 1.
3459+21=3459+20+1=3479+1=34803459 + 21 = 3459 + 20 + 1 = 3479 + 1 = \boxed{3480}
1dFind easy ways to solve: 5010+955010 + 95Show solution
Easy way: 5010+95=5010+90+5=5100+5=51055010 + 95 = 5010 + 90 + 5 = 5100 + 5 = \boxed{5105}
1eFind easy ways to solve: 4990+3104990 + 310Show solution
Easy way: 4990+310=5000+300=53004990 + 310 = 5000 + 300 = \boxed{5300}
(Since 4990+10=50004990 + 10 = 5000, and 31010=300310 - 10 = 300, so 5000+300=53005000 + 300 = 5300.)
1fFind easy ways to solve: 7844157844 - 15Show solution
Easy way: Subtract 10, then subtract 5.
784415=7844105=78345=78297844 - 15 = 7844 - 10 - 5 = 7834 - 5 = \boxed{7829}
1gFind easy ways to solve: 260+240260 + 240Show solution
Easy way: 260+240=260+240260 + 240 = 260 + 240. Notice 260+240=500260 + 240 = 500 (since 6+4=106+4=10, so 260+240=500260+240 = 500).
500\boxed{500}
1hFind easy ways to solve: 15751251575 - 125Show solution
Easy way: 1575125=157510025=147525=14501575 - 125 = 1575 - 100 - 25 = 1475 - 25 = \boxed{1450}
1iFind easy ways to solve: 3999+2903999 + 290Show solution
Easy way: 3999+290=4000+289=42893999 + 290 = 4000 + 289 = \boxed{4289}
(Add 1 to 3999 to get 4000, subtract 1 from 290 to get 289.)
2Use the signs <, =, > as appropriate to compare the following without actually calculating.Show solution
Note: The specific comparisons in this question are shown in an image that is not visible. The general approach is:

Strategy for comparing without calculating:
1. If both sides have the same number added/subtracted, the side with the larger starting number is larger.
2. If one side adds more and the other adds less, compare the net effect.
3. Example: 3456+2003456 + 200 vs 3456+1993456 + 1993456 + 200 &gt; 3456 + 199 (adding more gives more).
4. Example: 50003005000 - 300 vs 50002995000 - 2995000 - 300 &lt; 5000 - 299 (subtracting more gives less).

Apply these reasoning strategies to each comparison in the image.
3Use the given information to find the values.Show solution
Note: The specific values and relationships for this question are shown in images that are not visible. The general approach is:

If you are given that, for example, +=500\triangle + \square = 500 and =300\triangle = 300, then:
=500300=200\square = 500 - 300 = 200

For each puzzle:
1. Identify the known values and the operation.
2. Use inverse operations (if A+B=CA + B = C, then B=CAB = C - A; if AB=CA - B = C, then A=C+BA = C + B).
3. Substitute and solve step by step.

Please refer to the actual textbook images for the specific numbers and shapes used in each puzzle.

Final Exercise — Add and Subtract

1aAdd: 2783 + 378Show solution
2783+  378\begin{array}{r} 2783 \\ +\; 378 \\ \hline \end{array}
- O: 3+8=113+8=11 → write 1, carry 1
- T: 8+7+1=168+7+1=16 → write 6, carry 1
- H: 7+3+1=117+3+1=11 → write 1, carry 1
- Th: 2+0+1=32+0+1=3
3161\boxed{3161}
1bAdd: 8948 + 97Show solution
8948+  97\begin{array}{r} 8948 \\ +\; 97 \\ \hline \end{array}
- O: 8+7=158+7=15 → write 5, carry 1
- T: 4+9+1=144+9+1=14 → write 4, carry 1
- H: 9+0+1=109+0+1=10 → write 0, carry 1
- Th: 8+0+1=98+0+1=9
9045\boxed{9045}
1cAdd: 7006 + 367Show solution
7006+  367\begin{array}{r} 7006 \\ +\; 367 \\ \hline \end{array}
- O: 6+7=136+7=13 → write 3, carry 1
- T: 0+6+1=70+6+1=7
- H: 0+3=30+3=3
- Th: 77
7373\boxed{7373}
1dAdd: 8009 + 485Show solution
8009+  485\begin{array}{r} 8009 \\ +\; 485 \\ \hline \end{array}
- O: 9+5=149+5=14 → write 4, carry 1
- T: 0+8+1=90+8+1=9
- H: 0+4=40+4=4
- Th: 88
8494\boxed{8494}
1eAdd: 6062 + 3809Show solution
6062+  3809\begin{array}{r} 6062 \\ +\; 3809 \\ \hline \end{array}
- O: 2+9=112+9=11 → write 1, carry 1
- T: 6+0+1=76+0+1=7
- H: 0+8=80+8=8
- Th: 6+3=96+3=9
9871\boxed{9871}
1fAdd: 3792 + 2688Show solution
3792+  2688\begin{array}{r} 3792 \\ +\; 2688 \\ \hline \end{array}
- O: 2+8=102+8=10 → write 0, carry 1
- T: 9+8+1=189+8+1=18 → write 8, carry 1
- H: 7+6+1=147+6+1=14 → write 4, carry 1
- Th: 3+2+1=63+2+1=6
6480\boxed{6480}
1gAdd: 4999 + 3888Show solution
4999+  3888\begin{array}{r} 4999 \\ +\; 3888 \\ \hline \end{array}
- O: 9+8=179+8=17 → write 7, carry 1
- T: 9+8+1=189+8+1=18 → write 8, carry 1
- H: 9+8+1=189+8+1=18 → write 8, carry 1
- Th: 4+3+1=84+3+1=8
8887\boxed{8887}
1hAdd: 5005 + 4895Show solution
5005+  4895\begin{array}{r} 5005 \\ +\; 4895 \\ \hline \end{array}
- O: 5+5=105+5=10 → write 0, carry 1
- T: 0+9+1=100+9+1=10 → write 0, carry 1
- H: 0+8+1=90+8+1=9
- Th: 5+4=95+4=9
9900\boxed{9900}
1iAdd: 5768 + 4053Show solution
5768+  4053\begin{array}{r} 5768 \\ +\; 4053 \\ \hline \end{array}
- O: 8+3=118+3=11 → write 1, carry 1
- T: 6+5+1=126+5+1=12 → write 2, carry 1
- H: 7+0+1=87+0+1=8
- Th: 5+4=95+4=9
9821\boxed{9821}
1jAdd: 3480 + 479Show solution
3480+  479\begin{array}{r} 3480 \\ +\; 479 \\ \hline \end{array}
- O: 0+9=90+9=9
- T: 8+7=158+7=15 → write 5, carry 1
- H: 4+4+1=94+4+1=9
- Th: 33
3959\boxed{3959}
2aSubtract: 4456 − 2768Show solution
4456  2768\begin{array}{r} 4456 \\ -\; 2768 \\ \hline \end{array}
- O: 686-8: borrow, 168=816-8=8, T becomes 4
- T: 464-6: borrow, 146=814-6=8, H becomes 3
- H: 373-7: borrow, 137=613-7=6, Th becomes 3
- Th: 32=13-2=1
1688\boxed{1688}
2bSubtract: 5300 − 467Show solution
5300  467\begin{array}{r} 5300 \\ -\; 467 \\ \hline \end{array}
- O: 070-7: borrow chain. T is 0, H is 3→2, T 0→10→9, O 0→10
- O: 107=310-7=3
- T: 96=39-6=3
- H: 242-4: borrow, 124=812-4=8, Th becomes 4
- Th: 40=44-0=4
4833\boxed{4833}
2cSubtract: 8067 − 4546Show solution
8067  4546\begin{array}{r} 8067 \\ -\; 4546 \\ \hline \end{array}
- O: 76=17-6=1
- T: 64=26-4=2
- H: 050-5: borrow, 105=510-5=5, Th becomes 7
- Th: 74=37-4=3
3521\boxed{3521}
2dSubtract: 5302 − 1034Show solution
5302  1034\begin{array}{r} 5302 \\ -\; 1034 \\ \hline \end{array}
- O: 242-4: borrow, 124=812-4=8, T becomes 9
- T: 93=69-3=6... wait, T was 0, after borrowing becomes 9? Let me redo.
- O: 242-4: T is 0, borrow from H: H 3→2, T 0→10; O: 124=812-4=8
- T: 101=910-1=9... No. T becomes 10 after borrowing, then lends 1 to O, so T = 9. T: 93=69-3=6
- H: 20=22-0=2
- Th: 51=45-1=4
4268\boxed{4268}
2eSubtract: 8004 − 3107Show solution
8004  3107\begin{array}{r} 8004 \\ -\; 3107 \\ \hline \end{array}
- O: 474-7: borrow chain. T is 0, H is 0, borrow from Th: Th 8→7, H 0→10→9, T 0→10→9, O 4→14
- O: 147=714-7=7
- T: 90=99-0=9
- H: 91=89-1=8
- Th: 73=47-3=4
4897\boxed{4897}
2fSubtract: 3400 − 897Show solution
3400  897\begin{array}{r} 3400 \\ -\; 897 \\ \hline \end{array}
- O: 070-7: borrow chain. T 0→borrow from H: H 4→3, T 0→10→9, O 0→10
- O: 107=310-7=3
- T: 99=09-9=0
- H: 383-8: borrow, 138=513-8=5, Th becomes 2
- Th: 20=22-0=2
2503\boxed{2503}
2gSubtract: 9382 − 4857Show solution
9382  4857\begin{array}{r} 9382 \\ -\; 4857 \\ \hline \end{array}
- O: 272-7: borrow, 127=512-7=5, T becomes 7
- T: 75=27-5=2
- H: 383-8: borrow, 138=513-8=5, Th becomes 8
- Th: 84=48-4=4
4525\boxed{4525}
2hSubtract: 7561 − 2933Show solution
7561  2933\begin{array}{r} 7561 \\ -\; 2933 \\ \hline \end{array}
- O: 131-3: borrow, 113=811-3=8, T becomes 5
- T: 53=25-3=2
- H: 595-9: borrow, 159=615-9=6, Th becomes 6
- Th: 62=46-2=4
4628\boxed{4628}
2iSubtract: 6478 − 5986Show solution
6478  5986\begin{array}{r} 6478 \\ -\; 5986 \\ \hline \end{array}
- O: 86=28-6=2
- T: 787-8: borrow, 178=917-8=9, H becomes 3
- H: 393-9: borrow, 139=413-9=4, Th becomes 5
- Th: 55=05-5=0
492\boxed{492}
2jSubtract: 3444 − 2555Show solution
3444  2555\begin{array}{r} 3444 \\ -\; 2555 \\ \hline \end{array}
- O: 454-5: borrow, 145=914-5=9, T becomes 3
- T: 353-5: borrow, 135=813-5=8, H becomes 3
- H: 353-5: borrow, 135=813-5=8, Th becomes 2
- Th: 22=02-2=0
889\boxed{889}
3Fill the squares with the numbers 1–9. The difference between any two neighbouring squares (connected by a line) must be odd. Can you find other ways to fill the squares? Can you do the same thing such that the difference between any two neighbouring squares is even?Show solution
Key Concept: The difference between two numbers is odd only when one number is even and the other is odd (odd − even = odd, even − odd = odd). The difference is even only when both numbers are the same parity (both odd or both even).

Part 1: Difference between neighbours must be ODD

This means every pair of neighbouring squares must have one odd and one even number. This is like a 2-colouring (checkerboard) of the graph — alternate odd and even numbers.

Using numbers 1–9 (five odd: 1,3,5,7,9 and four even: 2,4,6,8):

One possible arrangement (assuming a simple chain or cross shape — the exact shape is in an image not visible):

For a row of squares: place them alternating odd-even-odd-even…
Example for 5 squares in a row: 1, 2, 3, 4, 5
- 12=1|1-2|=1 (odd) ✓
- 23=1|2-3|=1 (odd) ✓
- 34=1|3-4|=1 (odd) ✓
- 45=1|4-5|=1 (odd) ✓

Another arrangement: 9, 4, 7, 2, 5, 8, 3, 6, 1 (alternating odd-even throughout).

There are many possible arrangements — any arrangement that alternates odd and even numbers in neighbouring positions will work.

Part 2: Difference between neighbours must be EVEN

This means every pair of neighbours must both be odd or both be even.

Group all odd numbers together and all even numbers together in connected regions.

Example: Place odd numbers (1,3,5,7,9) in one connected group and even numbers (2,4,6,8) in another, with no odd-even neighbours.

For a row: 1, 3, 5, 7, 9 — all differences are even ✓
Or: 2, 4, 6, 8 for four squares.

For a mixed arrangement, ensure no odd number is adjacent to an even number.

Conclusion: Yes, there are many ways to fill the squares for both conditions. The key rule is:
- Odd differences: alternate odd and even numbers.
- Even differences: keep same-parity numbers as neighbours.

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