Estimation (Intro) — Answer Key
Part A: Sort the Words
Sort each word or number into the correct category box.
1. Sort each number by how it rounds to the nearest 10.
Rounds DOWN
134452 Rounds UP
286719 13 and 44 and 52 have ones digits below 5 so they round down. 28, 67, and 19 have ones 5 or higher so they round up.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. Round 34 to the nearest 10: 30
34 is between 30 and 40. The ones digit 4 is less than 5, so 34 rounds down to 30.
2. Round 56 to the nearest 10: 60
56 sits between 50 and 60. Ones digit 6 is 5 or more, so 56 rounds up to 60.
3. Round 72 to the nearest 10: 70
72 is between 70 and 80. The ones digit 2 is less than 5, so 72 rounds down to 70.
4. Round 48 to the nearest 10: 50
48 sits between 40 and 50. Ones digit 8 is 5 or more, so 48 rounds up to 50.
5. Round 21 to the nearest 10: 20
21 is between 20 and 30. The ones digit 1 is less than 5, so 21 rounds down to 20.
Part C: True or False?
Read each statement. Circle True or False.
1. The number 37 rounds to 40.
True False
The ones digit is 7. Since 7 is 5 or more, 37 rounds up to 40.
2. The number 62 rounds to 70.
True False
62 has ones digit 2, which is less than 5, so it rounds down to 60, not up to 70.
3. The number 83 rounds to 80.
True False
Since the ones digit 3 is less than 5, 83 rounds down to 80.
4. The number 19 rounds to 10.
True False
19 has ones digit 9, which is 5 or more. So 19 rounds up to 20, not down to 10.