Estimation of whole number addition and subtraction.

Estimation of Whole Number Addition and Subtraction

To estimate means to find an answer that is close to the exact answer. The key with estimation is to only use it in instances that don’t require an exact answer. 

Estimation means to find an answer that makes sense and works with the problem, but is not necessarily exact.

You can estimate sums (the answers to addition problems), and differences (the answers to subtraction problems). The first step in estimating a sum or a difference is to round the numbers, by changing them to the nearest power of ten, hundred, thousand, etc. Round the numbers first, then use mental math to estimate an answer.
When rounding, follow these rounding rules:When rounding, follow these rounding rules:When rounding, follow these rounding rules:

1. If the number being rounded is less than 5, round down.

1. If the number being rounded is 5 or greater, round up.

Some key things to think about when estimating:

1. The estimate must make sense for the problem.
2. The estimate must be reasonable.
3. The estimate must be close to the exact answer.
4. If none of the above fit the estimate,  use exact math for the problem.

Watch the video to know more about rounding numbers.

Solve: Post your answers in the comment box