Let's say you want to figure out how much bottled water that you need for a customer conference (total attendees × 4 days × 3 bottles per day) or the reimbursement travel cost for a business trip (total miles × .46). There are several ways to multiply numbers.
What do you want to do?
Multiply numbers in a cell
To do this task, use the * (asterisk) arithmetic operator.
For example, if you type the following formula in a cell:
=5*10
The cell displays the following result:
50
Multiply a range of numbers by a number
Important This procedure replaces the numbers in the range with the result of the multiplication.

In an empty cell, enter the number that you want to multiply by.

Select the cell, and on the Home tab, in the Clipboard group, click Copy .

Select the range of numbers that you want to multiply.

On the Home tab, in the Clipboard group, click the arrow below Paste, and then click Paste Special.

Under Operation, click Multiply.

Click OK.

Delete the content of the cell entered in the first step.
Multiply numbers in different cells by using a formula
To do this task, use the asterisk (*) operator or the PRODUCT function.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example

Create a blank workbook or worksheet.

Select the example in the Help topic.
Note: Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In the worksheet, select cell A1, and press CTRL+V.

To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.

