# Math

posted by on .

Here is the original question: Give an estimate for the following expression: 978*66. Is the exact answer going to be greater than or less than the estimate? Here is what I have: I rounded 978 to 1000 and 66 to 70. 1000*70=70,000 the actual answer was 978*66=64,448 so the estimation was greater than the actual answer. Did I do this problem right? I used the rounding technique. Thanks.

• Math - ,

However, you may want to review your reasoning.

What you said
I rounded 978 to 1000 and 66 to 70. 1000*70=70,000 the actual answer was 978*66=64,448 so the estimation was greater than the actual answer.

seems to tell me that you conclude that you were over-estimating after calculating the exact answer, which is not what is intended.

You are expected to determine if you answer is over- or under-estimating without calculating the exact answer.

Your teacher may prefer to see a reasoning as follows:
"I rounded 978 to 1000 and 66 to 70. 1000*70=70,000. Since I rounded up both multiplicands, the estimation was greater than the actual answer.
Check: 70000>978*66=64,448"