Estimation (Intro) — Answer Key
Part A: Sort the Words
Sort each word or number into the correct category box.
1. Decide which hundred each number is closest to, then sort it into rounds to 100-300 or rounds to 400-600.
Rounds to 100, 200, or 300
150270340210 Rounds to 400, 500, or 600
520480 Sorting by nearest hundred introduces the next big rounding skill for Grade 2 and builds estimation sense.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 150 rounds up to the nearest hundred of 200.
Just like ones, a tens digit of 5 rounds a number up, so 150 becomes 200.
2. 270 rounds to the nearest hundred of 300.
270 is closer to 300 than to 200 because 70 is more than halfway between 0 and 100.
3. 340 rounds to the nearest hundred of 300.
40 is less than halfway to 100, so 340 rounds down to 300.
4. 520 rounds to the nearest hundred of 500.
20 is closer to 0 than to 100, so 520 rounds down to 500.
5. 480 rounds to the nearest hundred of 500.
80 is past halfway to 100, so 480 rounds up to 500.
Part C: True or False?
Read each statement. Circle True or False.
1. 210 rounds to 200 because the tens digit is 1.
True False
Since 10 is less than halfway to 100, 210 rounds down to 200.
2. 150 rounds down to 100 because 5 rounds down.
True False
A 5 always rounds up, so 150 rounds up to 200, not down to 100.
3. 340 is closer to 300 than to 400.
True False
340 is only 40 away from 300 but 60 away from 400, so it is closer to 300.
4. 520 and 480 both round to the same hundred.
True False
520 rounds down to 500 and 480 rounds up to 500, so both round to 500.