Rounding to Nearest 10 and 100 — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 64 rounded to the nearest ten is 60.
The ones digit in 64 is 4, which is less than 5, so 64 rounds down to 60.
2. 317 rounded to the nearest hundred is 300.
The tens digit in 317 is 1, which is less than 5, so 317 rounds down to 300.
3. 92 rounded to the nearest ten is 90.
The ones digit in 92 is 2, which is less than 5, so 92 rounds down to 90.
4. 673 rounded to the nearest hundred is 700.
The tens digit in 673 is 7, which is 5 or greater, so 673 rounds up to 700.
5. 27 + 54 is about 80 when you round each number to the nearest ten.
Round 27 down to 30 and 54 down to 50, then add: 30 + 50 = 80. Rounding first makes the addition easier to do in your head.
6. 438 rounded to the nearest ten is 440.
The ones digit in 438 is 8, which is 5 or greater, so 438 rounds up to 440.
7. 250 rounded to the nearest hundred is 300.
The tens digit in 250 is exactly 5, and the rule says to round up when the digit is 5. So 250 rounds up to 300.
8. 76 - 29 is about 50 when you round each number to the nearest ten.
Round 76 up to 80 and 29 down to 30, then subtract: 80 - 30 = 50. Rounding first gives a quick estimate.
9. 555 rounded to the nearest hundred is 600.
The tens digit in 555 is 5, and when the digit is exactly 5, you round up. So 555 rounds up to 600.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
83
→ 80
50
350
→ 400
400
512
→ 500
500
46
→ 50
80
Correct matches: 83 → 80; 350 → 400; 512 → 500; 46 → 50.