Let's say you want to round a number to the nearest whole number because decimal values are not significant to you. Or, you want to round a number to multiples of 10 to simplify an approximation of amounts. There are several ways to round a number.
Change the number of decimal places displayed without changing the number
On a worksheet

Select the cells that you want to format.

To display more or fewer digits after the decimal point, on the Home tab, in the Number group, click Increase Decimal or Decrease Decimal .
In a builtin number format

On the Home tab, in the Number group, click the arrow next to the list of number formats, and then click More Number Formats.

In the Category list, depending on the data type of your numbers, click Currency, Accounting, Percentage, or Scientific.

In the Decimal places box, enter the number of decimal places that you want to display.
Round a number up
Use the ROUNDUP function. In some cases, you may want to use the EVEN and the ODD functions to round up to the nearest even or odd number.
Round a number down
Use the ROUNDDOWNfunction.
Round a number to the nearest number
Use the ROUND function.
Round a number to a near fraction
Use the ROUND function.
Round a number to a significant digit
Significant digits are digits that contribute to the accuracy of a number.
The examples in this section use the ROUND, ROUNDUP, and ROUNDDOWN functions. They cover rounding methods for positive, negative, whole, and fractional numbers, but the examples shown represent only a very small list of possible scenarios.
The following list contains some general rules to keep in mind when you round numbers to significant digits. You can experiment with the rounding functions and substitute your own numbers and parameters to return the number of significant digits that you want.

When rounding a negative number, that number is first converted to its absolute value (its value without the negative sign). The rounding operation then occurs, and then the negative sign is reapplied. Although this may seem to defy logic, it is the way rounding works. For example, using the ROUNDDOWN function to round 889 to two significant digits results in 880. First, 889 is converted to its absolute value of 889. Next, it is rounded down to two significant digits results (880). Finally, the negative sign is reapplied, for a result of 880.

Using the ROUNDDOWN function on a positive number always rounds a number down, and ROUNDUP always rounds a number up.

The ROUND function rounds a number containing a fraction as follows: If the fractional part is 0.5 or greater, the number is rounded up. If the fractional part is less than 0.5, the number is rounded down.

The ROUND function rounds a whole number up or down by following a similar rule to that for fractional numbers; substituting multiples of 5 for 0.5.

As a general rule, when you round a number that has no fractional part (a whole number), you subtract the length from the number of significant digits to which you want to round. For example, to round 2345678 down to 3 significant digits, you use the ROUNDDOWN function with the parameter 4, as follows: = ROUNDDOWN(2345678,4). This rounds the number down to 2340000, with the "234" portion as the significant digits.
Round a number to a specified multiple
There may be times when you want to round to a multiple of a number that you specify. For example, suppose your company ships a product in crates of 18 items. You can use the MROUND function to find out how many crates you will need to ship 204 items. In this case, the answer is 12, because 204 divided by 18 is 11.333, and you will need to round up. The 12th crate will contain only 6 items.
There may also be times where you need to round a negative number to a negative multiple or a number that contains decimal places to a multiple that contains decimal places. You can also use the MROUND function in these cases.