# Formulas

You use a formula to do basic math, such as addition or subtraction, using numbers, cell references, or even other formulas and functions. The process is slightly different than if you were writing them on paper:

- Every formula must start with an "=". This is how Excel knows you will be doing math
- The "operators", or mathmatical symbols, for excel are "+" for addition, "-" for subtraction, "*" for multiplication, and "/" for division
- Remember when you are writing a formula to hit the enter key when you are finished. Clicking on cells often will add them to the formula instead of displaying the result

For a simple example, we will add another "Total" column in E3. In E5, write the formula

=B5 + C5 + D5

You will notice that as you write cell names the cell will light up. This helps you ensure that you are using the right cell names. When you have this done, fill
the column down to E8.