Estimation is used to get a sensible approximate answer by replacing numbers with simpler, nearby values. It helps you judge whether a calculation is reasonable and is often used before or after finding an exact answer.

To estimate a calculation:

• Round the numbers to convenient values (such as 10, 100, or 1 significant figure)
• Use these rounded numbers to perform the calculation mentally or quickly

Examples:

• 49 × 18 (882) can be estimated as 50 × 20 = 1,000
• 3.98 + 6.12 (10.1) can be estimated as 4 + 6 = 10
• 602 ÷ 9 (66.88...) can be estimated as 600 ÷ 10 = 60

The goal is not accuracy, but sense-checking. Estimates should be quick, simple, and close enough to spot large errors.

You should be able to:

• Choose appropriate values to round to
• Estimate answers to calculations
• Use estimates to check exact solutions

Estimation is a powerful tool for building number sense and avoiding mistakes in longer calculations.

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