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:
340 rounded to the nearest hundred is 400.
Corrected: 340 rounded to the nearest hundred is 300 because 4 is less than 5 so we round down.
To round 340 to the nearest hundred, look at the tens digit. The tens digit is 4, which is less than 5, so we round down and keep the hundreds at 3, giving 300.
2. Fix the sentence:
872 rounded to the nearest hundred is 800.
Corrected: 872 rounded to the nearest hundred is 900 because 7 is 5 or greater so we round up.
The tens digit of 872 is 7, and 7 is 5 or greater, so we round up. The hundreds digit moves from 8 to 9, giving 900.
3. Fix the sentence:
550 rounded to the nearest hundred is 500.
Corrected: 550 rounded to the nearest hundred is 600 because when the tens digit is exactly 5 we round up.
When the tens digit is exactly 5, we round up. So 550 rounds up to 600 because the 5 in the tens place pushes the hundreds digit from 5 to 6.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 230 rounded to the nearest hundred is 200.
The tens digit in 230 is 3, which is less than 5, so 230 rounds down. The hundreds digit stays at 2, giving 200.
2. 678 rounded to the nearest hundred is 700.
Look at the tens digit of 678 — it is 7. Since 7 is 5 or greater, we round up from 600 to 700.
3. 450 rounded to the nearest hundred is 500.
The tens digit in 450 is 5, and the rule says 5 or more rounds up. So 450 rounds up to 500.
4. 149 rounded to the nearest hundred is 100.
Even though 149 looks close to 200, the tens digit is 4. Since 4 is less than 5, we round down to 100.
Part C: True or False?
Read each statement. Circle True or False.
1. When rounding to the nearest hundred, you look at the tens digit.
True False
True. When rounding to the nearest hundred, the tens digit is the deciding digit — it tells you whether to round the hundreds up or leave it the same.
2. 750 rounded to the nearest hundred is 700.
True False
False. The tens digit in 750 is 5, so we round up, not down. That makes 750 round to 800, not 700.
3. 310 rounded to the nearest hundred is 300.
True False
True. The tens digit in 310 is 1, which is less than 5, so 310 rounds down to 300.