Estimation of sums of whole numbers involves rounding addends to an appropriate place value or using compatible numbers, then combining the resulting approximate values while preserving the sum’s reasonable magnitude. The estimate is understood as an approximation whose accuracy depends on the chosen precision, and it can be compared with the exact sum to detect computational errors and judge reasonableness in later work with larger numbers and quantitative problem solving.
To estimate a sum, round each addend to the same place value, then add the rounded numbers. The result is an approximation, not the exact answer.
Example: Estimate by rounding to the nearest hundred.
Round each number:
Add the rounded numbers:
So, the estimated sum is:
The exact sum is , which is very close to the estimate. This shows that the estimate is reasonable.
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