As with all basic math operations in Excel, multiplying two or more numbers involves creating a formula.
Important points to remember about Excel formulas:
 Formulas in Excel always begin with the equal sign ( = ).
 The equal sign always goes in the cell where you want the answer to be displayed.
 The multiplication sign or operator used in Excel formulas is the asterisk ( * ) symbol.
Using Cell References in Formulas
Although it is possible to enter numbers directly into a formula, it is much better to enter the data into worksheet cells and then use the addresses or references of those cells in the formula.
The main advantage of using cell references in a formula, rather than the actual data, is that, if at a later date, it becomes necessary to change the data, it is a simple matter of replacing the data in the target cells rather than rewriting the formula.
The results of the formula will update automatically once the data in the target cells change.
Entering Cell References Using Pointing
Also, even though it is possible to just type the cell references to be used in the formula, a better approach is to use pointing to add the cell references.
Pointing involves clicking on the target cells containing the data with the mouse pointer to add the cell reference to the formula. The benefits of using this approach is that it minimizes the possibility of errors created by typing in the wrong cell reference.
Multiplication Formula Example
As shown in the image above, this example creates a formula in cell C1 that will multiply the data in cell A1 by the data in A2.
The finished formula in cell E1 will be:
= A1 * A2
Entering the Data

Type the number 10 in cell A1 and press the Enter key on the keyboard,

Type the number 20 in cell A2 and press the Enter key,
Entering the Formula

Click on cell C1 to make it the active cell  this is where the results of the formula will be displayed.

Type = (an equal sign) into cell C1.

Click on cell A1 with the mouse pointer to enter that cell reference into the formula.

Type * ( an asterisk symbol) after A1.

Click on cell A2 with the mouse pointer to enter that cell reference.

Press the Enter key on the keyboard to complete the formula.

The answer 200 should be present in cell C1.

Even though the answer is displayed in cell C1, clicking on that cell will show the actual formula = A1 * A2 in the formula bar above the worksheet.
Changing the Formula Data
To test the value of using cell references in a formula:
 Change the number in cell A2 from 20 to 5 and press the Enter key on the keyboard.
The answer in cell C1 should automatically update to 50 to reflect the change in data in cell A2.
Changing the Formula
If it becomes necessary to correct or change a formula, two of the best options are:
 Doubleclick the formula in the worksheet to place Excel in Edit mode and then make changes to the formula. This works best for minor changes.
 Click once on the cell containing the formula and rewrite the entire formula. This method is best for major changes.
Creating More Complex Formulas
To write more complex formulas that include multiple operations  such as subtraction, addition, and division, as well as multiplication  just add the correct mathematical operators in the correct order followed by the cell references containing the data.
Before mixing different mathematical operations together in a formula, however, it is important to understand the order of operations that Excel follows when evaluating a formula.
For practice, try this step by step example of a more complex formula.