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How to Estimate With Decimals

You may have heard of "rounding up" and "rounding down" when someone is talking about numbers. Sometimes with math, numbers will be estimated to simplify problems. This method requires a formula that is followed for both whole numbers and decimals. While the formula is basically the same for both types of values, there are a few details and terminology that are different. With practice, you will be able to estimate some decimals in your head.

Instructions

- 1
  Look for the place value that you would like to estimate or round. The term "place value" in this case stands for the number for which you are trying to figure out an estimate.
- 2
  Review your decimal place terminology. From the decimal point going towards the right, each number has a name -- tenths, hundredths, thousandths, ten thousandths, hundred thousandths and so on. For example, in the number 8.2375, the 2 is in the tenths place, the 3 is in the hundredths place, the 7 is in the thousandths place and the 5 is in the ten thousandths place.
- 3
  Round the place value up one number if the number to the right of the place value that you want to estimate is 5 or greater. For example, to round 8.2375 to the nearest hundredth, 3 is the place value you need to round. Look directly to the right of 3 and you will see a 7. Because 7 is greater than 5, you will be rounding the place value of 3 up. The end result will be 8.24.
- 4
  Keep the place value the same if the number to the right of the place value that you want to estimate is 4 or less. For example, to round 8.2375 to the nearest tenth, which is 2, look directly to the right of the 2 and you will see a 3. The number 3 is less than 4, so the place value of 2 will stay the same. The end result will be 8.2.

Numerology