Rounding numbers gives your numbers that are close in value to the starting numbers, but are less exact. For example, rounding 241 to the nearest ten gives you 240. Rounding 243 to the nearest ten also is 240, while 246 rounds to 250. Here are the rules for rounding numbers and sums. Also, learn about rounding in significant figures.

Rules for Rounding Numbers

It may surprise you that there are lots of different ways of rounding numbers. Each method has its own rules, advantages, and disadvantages. However, the most common method rounds up when the digit in question is followed by a 5 or higher:

• Round up if the digit you are rounding is followed by a 5, 6, 7, 8, or 9. For example, 48 rounded to the nearest ten is 50.

• Round down if the digit you are rounding is followed by a 0, 1, 2, 3, or 4. For example, 23 rounded to the nearest 10 is 20.

Here is a rhyme to help you remember:

Find your place,

look next door.

5 or greater, add one more.

Finding Your Place

First, decide what place you are rounding to, whether it’s the nearest, tenth, one, ten, hundred, thousand, and so on. Here are some examples:

• 3947 rounded to the nearest ten is 3950

• 3947 rounded to the nearest hundred is 3900

• 3947 rounded to the nearest thousand is 4000

Note that all of the digits to the right of the place you are rounding become zeros. Rounding decimals works the same way. For example:

• 21.0538 rounded to the nearest one is 21

• 21.0538 rounded to the nearest tenth is 21.1

• 21.0538 rounded to the nearest hundredth is 21.05

• 21.0538 rounded to the nearest thousandth is 21.054

Note: you do not add zeros to the right of the decimal point.