Smart Math guide · Number Sense

Estimate Before Exact Work

A quick estimate gives you a target range and catches many calculator or arithmetic errors.

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The method

How to use it

  1. Round each value to one or two useful digits.
  2. Compute the rough answer.
  3. Compare the exact answer to the estimate.
Worked example

See it in action

49.8 × 19.7 ≈ 50 × 20 = 1000; exact work should land near 1000.

Check your thinking

How to verify it

If an exact result were 98 or 9800, the estimate would flag it.

Keep learning

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