Estimating is perfect for shopping aisles and dinner tables. Calculators win when the stakes are high, the formula is non-linear, or someone else needs to audit your work.
Good times to estimate
- Comparing two sale prices in a store
- Splitting a bill roughly among friends
- Checking whether a quoted number is in the right ballpark
Rule of thumb
If being off by 10% would not change your decision, estimate first.
When to calculate precisely
- Mortgage or loan payments
- Tax estimates and invoicing
- Medical screening indices like BMI
- Grades that affect academic standing
Best of both
Estimate first, then calculate to confirm.