Estimate sums, products, quotients, and percent results, then judge whether an exact answer is reasonable.
Estimate a sum with rounding
Problem
Estimate the sum of \(48.6\) and \(31.2\) by rounding each number to the nearest whole number and then adding the rounded numbers.
Big Picture
What this problem is really about
This sum is meant to be estimated at the whole-number level. We’ll round each addend independently by looking at its tenths digit, then add the two rounded values instead of the original decimals. That keeps the calculation simple while preserving the size of the sum.
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