Читать книгу Basic Math & Pre-Algebra All-in-One For Dummies (+ Chapter Quizzes Online) - Mark Zegarelli - Страница 49

When you know how to round numbers, you can use this skill in estimating values. Estimating saves you time by allowing you to avoid complicated computations and still get an approximate answer to a problem.

When you get an approximate answer, you don’t use an equals sign; instead, you use this wavy symbol, which means is approximately equal to: ≈.

Suppose you want to add these number: . This computation is tedious, and you may make a mistake. But you can make the addition easier by first rounding all the numbers to the nearest hundred and then adding:

The approximate answer is 3,800. This answer isn’t far off from the exact answer, which is 3,792.

5 Estimate by rounding all values to the nearest ten before adding.

6 Estimate by rounding all values to the nearest hundred before adding.

7 Estimate by rounding all values to the nearest hundred before adding and subtracting.

8 Estimate by rounding all values to the nearest thousand before adding and subtracting.