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Grade 3 Math · World 2: Add-and-Subtract Express · Level 17
Is It Reasonable?
Round to estimate, then check an answer against the estimate.
Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.
What children learn in Level 17
- An estimate is a close guess that helps you check your answer. Estimate 412 plus 289 by rounding to the nearest hundred.
- 412 rounds to 400, and 289 rounds to 300. 400 plus 300 is 700, so the answer should be close to 700.
- If someone says 412 plus 289 is 1,001, that's far from 700. Not reasonable! The real answer, 701, is close. Reasonable!
Georgia's K-12 Mathematics Standards:
- 3.PAR.2.2 — Apply part-whole strategies, properties of operations and place value understanding, to solve problems involving addition and subtraction within 10,000. Represent these problems using equations with a letter standing for the unknown quantity. Justify solutions.
- 3.NR.1.3 — Use place value understanding to round whole numbers within up to 1000 to the nearest 10 or 100.