Estimating means finding an answer that is close to the exact amount. We use estimation when we do not need the exact number, but we want to know about how much or about how many.
Estimating helps check if an answer makes sense before or after solving a problem exactly.
When estimating, round each number to a place value that makes the problem easier to solve, such as the nearest ten, hundred, or thousand. Then add or subtract the rounded numbers.
Always round both numbers before solving. This keeps your estimate balanced and reasonable.
When rounding a number, look at the digit to the right of your rounding place. If that digit is 5 or more, round up. If it is 4 or less, keep the rounding digit the same and change all digits to the right to zero.
Rounding makes numbers simpler and faster to work with, especially in multi-step problems.
In word problems, estimation helps you quickly find about how much something costs, how long something takes, or how far something is. It’s useful when an exact answer isn’t needed or before you solve precisely.
Use estimation to check if your exact calculation is reasonable. For example, if the exact total is 624, it is close to your estimate of 600—so your answer makes sense.
After solving a word problem, compare your exact answer to your estimate. If the numbers are close, your answer is probably reasonable. If they are far apart, check your work again.
Estimating before and after solving helps catch mistakes and builds number sense.