Texas Math Models

Is it reasonable?

4,367 + 2,258 = 6,625 Grade 4

the estimate is how you catch a wrong answer my estimate ≈ 6,700 my exact answer 6,625 vs close: the answer makes sense ✓ but if you ignored the thousands and got 625 … 625 is ten times too small: go back and check an estimate does not give the answer; it guards it

How this one works

How

compare your estimate to your exact answer; are they close?

Best when

you have finished and want to know if you can trust it.

The same problem, other ways