Rounding to Nearest 10 and 100 — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. What is 519 rounded to the nearest hundred?
A) 500
B) 510
C) 520
D) 600
The tens digit in 519 is 1, which is less than 5, so 519 rounds down to 500.
2. A baker makes 73 muffins and 48 cookies. About how many treats total when rounded to the nearest ten?
A) 110
B) 120
C) 130
D) 140
Round 73 down to 70 and 48 up to 50, then add: 70 + 50 = 120. This estimate tells the baker roughly how many treats were made.
3. Which of these numbers does NOT round to 700 when rounded to the nearest hundred?
A) 651
B) 738
C) 749
D) 643
The tens digit in 643 is 4, which is less than 5, so 643 rounds down to 600, not up to 700. The other choices all round to 700.
4. Rounding 385 to the nearest ten gives you what number?
A) 380
B) 390
C) 400
D) 300
The ones digit in 385 is 5, and the rule says to round up when the digit is exactly 5. So 385 rounds up to 390.
Part B: Fill in the Blank
Write the correct answer on each line.
1. 263 rounded to the nearest hundred is 300.
The tens digit in 263 is 6, which is 5 or greater, so 263 rounds up to 300.
2. 36 + 57 is about 100 when each number is rounded to the nearest ten.
Round 36 up to 40 and 57 up to 60, then add: 40 + 60 = 100. Rounding both numbers first makes the mental math simple.
3. 814 rounded to the nearest ten is 810.
The ones digit in 814 is 4, which is less than 5, so 814 rounds down to 810.
4. When rounding 350 to the nearest hundred, the answer is 400.
The tens digit in 350 is exactly 5, and the rule says to round up when the digit is 5. So 350 rounds up to 400.
5. 72 - 45 is about 20 when each number is rounded to the nearest ten.
Round 72 down to 70 and 45 up to 50, then subtract: 70 - 50 = 20. This estimate is close to the exact answer of 27.