Rounding Decimals

Your hand can quickly get tired if you try to write out every decimal in a math problem as far as you can, rather than rounding them. Knowing how to round decimals is very important, not only because it saves time, but because certain problems will require you to write out your answer to a certain decimal place. To learn how to properly round decimals, follow these steps.

Difficulty:

Moderately Easy

Instructions

1. Learn the different places of the decimal. In order to round to the nearest hundredth or thousandth, you with first need to know what place after the decimal point that is. The first place after the decimal is the tenths place, the second is the hundredths, and so on. So if you have the decimal .985, the 9 is in the tenths place, the 8 is in the hundredths place and the 5 is in the thousandths place.

2. Determine what place you need to round your decimal to. If your problem doesn't ask you to round to a particular decimal place, you can ask your teacher what place she prefers.

3. Look at the number in the decimal place that's to the immediate right of the decimal place you need to round to. For example, if you are asked to round .9857 to the nearest thousandth, look at the 7, because the 5 is in the thousandth place and 7 is in the decimal place to its immediate right.

4. Determine if that number is a 5 or higher. If it is, add one to the number in the decimal place to which you are rounding. If the number is less than 5, leave unchanged the number in the decimal place to which you are rounding. Using our previous example, we would determine that 7 is indeed greater than 5, so we would round our decimal to .986, since we added 1 to the 5. If we were dealing with the decimal .9854 instead, we would leave the 5 alone, and that would leave us with the decimal .985.

5. Know that, if you are adding 1 to the decimal place to which you are rounding, then you are rounding up (as is the case with the first example in the previous step). If you don't add 1 to the decimal place to which you are rounding, then you are rounding down, even though you aren't decreasing the value of that decimal place.