Question

Explain how an estimate helps you to place the decimal point when multiplying 3.7 x 5.1?

Answer 1

Since 3*5=15, then the answer to 3.7*5.1 should be close to that same value.

3.7*5.1=18.87

But if you were solving it by hand, and accidentally wrote the answer as 1.887 or 188.7. Estimating helps you know that you placed the decimal in the wrong area, Since the number isn't close to 15.