Front end estimating

Front end estimating is rounding the first significant number on any calculation as a rough estimate.

By rounding the first number in a sum you can make it easier but the answer wont be exactly correct

Sometimes the front end is more important.

Example 1

Estimate the following sum:

`4026+398+42`

Adding `4026+398+42` is tricky.

But adding `4000+400+40` is easy.

NOTE:

The real answer is `4466` and so you can see that `4440` is a worthy estimate.