A *whole number* is any number you can make by adding any number of *1s* to *0* -- including *0* itself. Some examples of whole numbers include 2, 5, 17, and 12,000. ** Rounding** is a process by which you take a precise number and re-state it as an approximation. One common means of rounding is using a

*number line,*a visual representation of where a decimal falls in comparison to the whole numbers on either side. However, when you round a decimal number to a whole number, you only need to pay attention to the tenths digit of the decimal to determine which direction to round.

## Rounding to a Whole Number

**Locate the tenths digit of the number you are rounding.** The tenths digit of a number is the digit directly to the right of the decimal point.

For example, the tenths digit of **6.178** is **1**. The tenths digit of **7.6** is **6**.

## Sciencing Video Vault

**Determine whether the tenths digit is less than 5.** This will determine whether how you round your number up or down. If the tenths digit is 5 or greater, you round up. If the tenths digit is less than 5 -- including 0 -- you round down.

When the tenths digit is 5 or greater, you *round up*. This means you **add 1 to the ones digit of your number,** the digit directly to the left of the decimal point. You then re-write your number without any digits to the right of the decimal point.

Take 43.78. The ones digit is 3, and the tenths digit is 7. Since 7 is 5 or greater, you add 1 to the ones digit, getting 44.78. You then re-write the number without the digits after the decimal point: 44. So 43.78 rounds to 44.

If the tenths digit is 4 or less, including 0, you *round down*. **The ones digit remains unchanged, and you re-write the number without the digits to the right of the decimal point.**

Say you're rounding 102.198. The tenths digit is 1, which is 4 or less, so you will round down. Re-write 102.198 without the decimal places: 102. So 102.198 rounds to 102.

#### TL;DR (Too Long; Didn't Read)

Note that negative numbers are not whole numbers. However, the same rules apply for rounding to the ones digit of a negative number: add 1 if the tenths digit is 5 or higher, do not change the ones digit if the tenths digit is 4 or lower.