Mathematics
Addition & Subtraction
Meta
9–10 yrs
Checking Answers by Rounding
用四舍五入验算结果
Description
Use rounding to check answers to calculations and determine appropriate levels of accuracy in context
Mastery Evidence
- Check 47,832 + 23,156 ≈ 48,000 + 23,000 = 71,000 to verify the exact answer 70,988
- Decide whether to round to the nearest 100 or 1,000 for a given estimation context
- Identify that a calculated answer of 3,421 cannot be correct because the estimate gives approximately 50,000
Assessment Prompt
If your child gets an answer of 4,213 for an addition, can they round the numbers to double-check — like '4,000 + 1,000 ≈ 5,000' — and spot if the answer seems way off?
