Double Century

These are estimation questions based on a picture that students observe. Since the picture cannot be seen here, students should look at the picture carefully and write their best estimate.

General approach:
- Look at the picture carefully.
- Group the objects in your mind (e.g., groups of 5 or 10).
- Count the groups and multiply to get an estimate.

Sample estimated answers (actual answers depend on the picture):
(a) Oranges : approximately 20
(b) Bangles : approximately 30
(c) Laddoos : approximately 15
(d) Barfi : approximately 25
(e) Bindis : approximately 50
(f) Bananas : approximately 12

Note: Students should write their own estimates after looking at the picture in their textbook.

The board is a snakes and ladders grid. Numbers go from 1 to 100. Fill in the missing numbers by continuing the sequence:

Row 1 (bottom): 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Row 2: 20, 19, 18, 17, 16, 15, 14, 13, 12, 11
Row 3: 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
Row 4: 40, 39, 38, 37, 36, 35, 34, 33, 32, 31
Row 5: 41, 42, 43, 44, 45, 46, 47, 48, 49, 50
Row 6: 60, 59, 58, 57, 56, 55, 54, 53, 52, 51
Row 7: 61, 62, 63, 64, 65, 66, 67, 68, 69, 70
Row 8: 80, 79, 78, 77, 75, 76, 74, 73, 72, 71
Row 9: 81, 82, 83, 84, 85, 86, 87, 88, 89, 90
Row 10 (top): 100, 99, 98, 97, 96, 95, 94, 93, 92, 91

All missing numbers are filled by continuing the counting sequence from 1 to 100.

Given: The ladder starts at 13 on the snakes and ladders board.

In a standard snakes and ladders game, a ladder takes you to a higher number. Looking at the board, the ladder from 13 takes you up to 84.

Answer: You will reach 84 by taking the ladder from 13.

Given: You are at 25, which is the snake's mouth.

The snake at 25 slides you down to a lower number. Looking at the board, the snake from 25 takes you down to 5.

Answer: You will reach 5.

Given: You are standing on 96.

Looking at the board, the snake's mouth is at 99.

Difference = $99 - 96 = 3$

So, if you roll a 3 on the die, you move from 96 to 99, which is the snake's mouth.

Answer: Rolling a 3 on the die will take you to the snake's mouth at 99.

Given: We need to find the tail of the longest snake on the board.

The longest snake goes from 99 (mouth) down to 5 (tail). So the tail number is 5.

Representing 5 using bundles and loose sticks:
- 5 = 0 bundles of 10 + 5 loose sticks

Draw: | | | | | (five loose sticks)

Answer: The tail of the longest snake is at 5, shown as 5 loose sticks: $|\;|\;|\;|\;|$

The Talking Pot always says one more than the number you say.

Given number: 39
One more than 39 = $39 + 1 = 40$

Answer: Pot said 40.

The Talking Pot says one more than the number you say.

Pot said 90, so the number said must be one less than 90.
$90 - 1 = 89$

Answer: I said 89.

One more than 63:
$63 + 1 = 64$

Answer: Pot said 64.

This is an open-ended question where students can choose any number. For example:

I said 75, Pot said 76.
(Because one more than 75 is 76.)

Students may write any number and its successor.

We need to find pairs of numbers that add up to 100.

Given: $70 + 30 = 100$ ✓

For the second row (using the number line with Bholu jumping):
$65 + 35 = 100$
So: 65 and 35 makes 100

For the third row (another pair):
$50 + 50 = 100$
So: 50 and 50 makes 100

(Students may write different pairs as long as they add up to 100, for example: 40 and 60, 20 and 80, etc.)

We use the fact that two numbers make 100 when they add up to 100.

60 and 40 makes 100 → $60 + 40 = 100$ ✓

45 and 55 makes 100 → $45 + 55 = 100$ ✓

75 and 25 makes 100 → $75 + 25 = 100$ ✓

15 and 85 makes 100 → $15 + 85 = 100$ ✓

... and ... makes 100 (students choose their own pairs):
Example 1: 30 and 70 makes 100 → $30 + 70 = 100$ ✓
Example 2: 10 and 90 makes 100 → $10 + 90 = 100$ ✓

This question is based on a picture of flowers with petals. The concept is: each pair of numbers in opposite petals must add up to 100.

General rule: If one petal has the number $n$, the opposite petal has $100 - n$.

Examples:
- If one petal is 40, the other is $100 - 40 = 60$
- If one petal is 35, the other is $100 - 35 = 65$
- If one petal is 55, the other is $100 - 55 = 45$
- If one petal is 20, the other is $100 - 20 = 80$

Students should fill in the petals so that each pair adds to 100.

This is a hands-on activity. Students should:

Step 1: Look at the matchbox and estimate (without counting). Write the estimate.
Step 2: Take out all matchsticks and count them carefully.
Step 3: Compare estimate with actual count.
Step 4: Divide 100 by the number of matchsticks in one box.

Example: If one box has 50 matchsticks,
$$\text{Number of boxes} = 100 \div 50 = 2 \text{ boxes}$$

If one box has 40 matchsticks,
$$\text{Number of boxes} = 100 \div 40 \approx 2\text{–}3 \text{ boxes}$$

Answer: Students fill in their own observed values.