Question

what is an instance when you might want to find an estimate for fraction sums or differences rather than an exact answer?

Answer 1

You might want to have estimates in some cases like if you say what is 1/3 of a dollar in cents. Now the answer would be .333333 that goes on forever (try it on a calculator). So you would need to round to 33 cents or $.33 for the answer.

Hope this helps :)