Estimate by Front-End Rounding
Front-end rounding is a quick way to make an estimate by keeping only the first digit or first place value that matters, then changing the rest of the number to zeros. It gives a reasonable answer without doing exact calculation.
How to do it
- Look at the first digit(s) of each number. Keep the leftmost place value that is important for the estimate.
- Round from the front by turning the remaining digits into zeros. This is not the same as regular rounding to the nearest ten or hundred; you are simplifying the number using its leading part.
- Use the rounded numbers to complete the operation.
- Simplify the result if needed.
Example idea
If a number is large, keep the front digit(s) and replace the rest with zeros before estimating. Then compute with those easier numbers.
Check your answer
- Make sure each original number was simplified in the same way.
- The estimate should be close to the exact answer, but it does not need to be exact.
- If the exact answer is given later, compare it to see whether your estimate makes sense.
Good habit
Use front-end rounding when you want a fast, sensible estimate and the exact calculation would take longer.