Estimate and judge reasonableness
4th Grade Math practice: A student says 398 × 6 is about 2,500. Is that reasonable. Part of extension: problem solving (Extension: Problem Solving).
~9 min
Use rounding and benchmark numbers to predict a reasonable result before or after solving exactly.
Rounding to Estimate
To check if a calculation is reasonable, round your numbers to the nearest ten or hundred first. This makes it easier to find a quick, approximate result in your head.
💡 Rounding turns difficult numbers into friendly numbers that are easy to add or multiply.