Rounding to Nearest 10 and 100 — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
47 rounded to the nearest ten is 40.
Corrected: 47 rounded to the nearest ten is 50 because 7 is 5 or greater so we round up.
When rounding to the nearest ten, the ones digit decides the direction. The ones digit in 47 is 7, and 7 is 5 or greater, so we round up to 50.
2. Fix the sentence:
82 rounded to the nearest ten is 90.
Corrected: 82 rounded to the nearest ten is 80 because 2 is less than 5 so we round down.
The ones digit in 82 is 2, which is less than 5, so we round down. That keeps the tens digit the same and gives 80.
3. Fix the sentence:
35 rounded to the nearest ten is 30.
Corrected: 35 rounded to the nearest ten is 40 because when the digit is exactly 5 we round up.
When the ones digit is exactly 5, the rule is to round up. So 35 rounds up to the next ten, which is 40.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 63 rounded to the nearest ten is 60.
The ones digit in 63 is 3, and 3 is less than 5, so we round down to 60. The 6 in the tens place stays the same.
2. 78 rounded to the nearest ten is 80.
Looking at the ones digit in 78, it is 8. Since 8 is 5 or greater, we round up, bumping 70 up to 80.
3. 24 rounded to the nearest ten is 20.
Since the ones digit in 24 is 4 and 4 is less than 5, the tens place stays put and 24 rounds down to 20.
4. 95 rounded to the nearest ten is 100.
The ones digit in 95 is 5, so we round up. Rounding 90 up to the next ten crosses into the hundreds, giving 100.
Part C: True or False?
Read each statement. Circle True or False.
1. When rounding to the nearest ten, you look at the ones digit.
True False
True. To round to the nearest ten, you look at the digit just to the right of the tens place — that is the ones digit — and use it to decide whether to round up or down.
2. 54 rounded to the nearest ten is 60.
True False
False. The ones digit in 54 is 4, which is less than 5, so 54 rounds down to 50, not up to 60.
3. If the ones digit is 5 or more, you round up to the next ten.
True False
True. The rule for rounding is that a ones digit of 5 or more rounds the number up to the next ten.