7th Grade · The Number System
Reasonableness
7.NS.A.3
Definition
The quality of an answer being sensible and close to the estimated value. Always estimate first, then check whether your exact answer is in the ballpark.
Examples
- 48 × 19 ≈ 50 × 20 = 1,000; the exact answer 912 is reasonable.
- A student says 48 × 19 = 9,120 — way off, so not reasonable.
Key rule
Estimate first to catch errors: is the answer the right size and the right sign?
Memory hook
Estimate, then sanity-check.