Instructions
Estimation is like making a smart guess! It helps you find an answer that is close to the real one, but it's much faster. We will practice by rounding numbers to the nearest 10.
Example: To estimate 28 + 41, you can round 28 to 30 and 41 to 40. Your smart guess is 30 + 40 = 70. The real answer is 69, so 70 is a great estimate!
Part 1: Rounding Practice
Round each number to the nearest 10. The first one is done for you!
| 23 → 20 | 48 → _____ |
| 71 → _____ | 85 → _____ |
| 16 → _____ | 97 → _____ |
Part 2: Estimate the Sum
Round each number to the nearest 10 to estimate the answer.
1. Sarah saw 42 butterflies in the garden. Then, 19 more flew in. About how many butterflies were there in total?
42 rounds to ______
19 rounds to ______
Estimated total: ______ + ______ = ______
2. You have 58 crayons, and your friend gives you 31 more. About how many crayons do you have now?
58 rounds to ______
31 rounds to ______
Estimated total: ______ + ______ = ______
Part 3: Estimate the Difference
Round each number to the nearest 10 to estimate the answer.
1. A baker made 88 cookies. He sold 39 of them. About how many cookies are left?
88 rounds to ______
39 rounds to ______
Estimated difference: ______ - ______ = ______
2. There are 63 birds sitting on a wire. 28 of them fly away. About how many birds are left on the wire?
63 rounds to ______
28 rounds to ______
Estimated difference: ______ - ______ = ______
Part 4: Smart Guessing Challenge!
Use estimation to check if the answers below are reasonable. Circle Yes or No.
1. Problem: 32 + 59 = 91
My estimate: 30 + 60 = 90. Is 91 a reasonable answer?
Yes / No
2. Problem: 78 - 19 = 100
My estimate: ______ - ______ = ______. Is 100 a reasonable answer?
Yes / No
3. Problem: 47 + 47 = 94
My estimate: ______ + ______ = ______. Is 94 a reasonable answer?
Yes / No
Answer Key
Part 1: Rounding Practice
48 → 50
71 → 70
85 → 90
16 → 20
97 → 100
Part 2: Estimate the Sum
1. 42 rounds to 40, 19 rounds to 20. Estimated total: 40 + 20 = 60
2. 58 rounds to 60, 31 rounds to 30. Estimated total: 60 + 30 = 90
Part 3: Estimate the Difference
1. 88 rounds to 90, 39 rounds to 40. Estimated difference: 90 - 40 = 50
2. 63 rounds to 60, 28 rounds to 30. Estimated difference: 60 - 30 = 30
Part 4: Smart Guessing Challenge!
1. Yes (The estimate 90 is very close to 91.)
2. My estimate: 80 - 20 = 60. Is 100 a reasonable answer? No
3. My estimate: 50 + 50 = 100. Is 94 a reasonable answer? Yes