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Estimation

Estimate sums by rounding to the nearest 10 (e.g. 48 + 52 ≈ 100).

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Estimation helps us quickly check if an answer is reasonable.
Round each number first, then add—it's faster than exact calculation!
We estimate when we don't need an exact answer.
Understand Estimation before you start

Read this if you're new to the topic—it will help you know what to do in each problem.

Estimation means getting a rough answer by rounding numbers first, then calculating. It's useful when you don't need an exact value.

For "about how much is 48 + 52?", round to the nearest 10: 48 → 50, 52 → 50, so 50 + 50 = 100. The exact answer is also 100.

Examples
48 + 52 ≈ 50 + 50 = 100
23 + 37 ≈ 20 + 40 = 60