Rounding to Nearest 10 and 100 — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 57 rounded to the nearest ten is 60.
The ones digit in 57 is 7, which is 5 or greater, so 57 rounds up to 60.
2. 462 rounded to the nearest hundred is 500.
The tens digit in 462 is 6, which is 5 or greater, so 462 rounds up to 500.
3. 34 rounded to the nearest ten is 30.
The ones digit in 34 is 4, which is less than 5, so 34 rounds down to 30.
4. 718 rounded to the nearest hundred is 700.
The tens digit in 718 is 1, which is less than 5, so 718 rounds down to 700.
5. 43 + 38 is about 80 when you round each number to the nearest ten.
Round 43 down to 40 and 38 up to 40, then add: 40 + 40 = 80. Estimating with rounded numbers makes mental math quicker.
6. 286 rounded to the nearest ten is 290.
The ones digit in 286 is 6, which is 5 or greater, so 286 rounds up to 290.
7. 450 rounded to the nearest hundred is 500.
The tens digit in 450 is exactly 5, and the rule says to round up when the digit is 5. So 450 rounds up to 500.
8. 93 - 36 is about 50 when you round each number to the nearest ten.
Round 93 down to 90 and 36 up to 40, then subtract: 90 - 40 = 50. Rounding before subtracting gives a quick estimate.
9. 845 rounded to the nearest hundred is 800.
The tens digit in 845 is 4, which is less than 5, so 845 rounds down to 800.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
44
→ 40
90
650
→ 700
200
173
→ 200
40
86
→ 90
700
Correct matches: 44 → 40; 650 → 700; 173 → 200; 86 → 90.