Comparison of Numbers

69

Step 1: 'Just before' means the number that comes directly before the given number on the number line. Step 2: On the number line, numbers go: ...67, 68, 69, 70, 71... Step 3: The number just before 70 is one less than 70. Step 4: 70 - 1 = 69. Step 5: So 69 comes just before 70. Common mistake: 60 is before 70 but NOT just before — it is 10 steps away, not 1 step away.

100

Step 1: 'Just after' means the number that comes directly after the given number. Step 2: The number just after any number is 1 more than that number. Step 3: 99 + 1 = 100. Step 4: So the number just after 99 is 100. Step 5: This is a special case — 100 is the number that comes after 99 and it is a 3-digit number! Common mistake: Some students say 90 comes after 99, but that is actually before 99.

55

Step 1: To find the greatest number, compare all the tens digits first. Step 2: Tens digits are: 45→4, 54→5, 44→4, 55→5, 40→4. Step 3: Numbers with 5 tens are 54 and 55 — these are the largest group. Step 4: Compare 54 and 55 — both have 5 tens. Compare ones: 54 has 4 ones, 55 has 5 ones. 55 > 54. Step 5: So 55 is the greatest number. Ascending order: 40 < 44 < 45 < 54 < 55. The last number is the greatest.

30

Step 1: To find the smallest number, look at the tens digits of all numbers. Step 2: Tens digits: 38→3, 83→8, 33→3, 88→8, 30→3. Step 3: Numbers with 3 tens are: 38, 33, 30 — these are the smallest group. Step 4: Compare ones digits of 38, 33, 30: ones are 8, 3, 0. The smallest ones digit is 0. Step 5: So 30 is the smallest number. In descending order: 88 > 83 > 38 > 33 > 30. The last number is the smallest.