To get Excel to perform calculations, such as addition or subtraction, we create a formula. Although writing a formula in Excel is similar to the way you would write a formula in math class, there a couple of important differences.
One difference is that a formula in Excel begins with the equal sign rather than ending with it. A second difference is that we normally do not put numbers in Excel formulas. Instead of numbers we enter cell references.
Each “box” on the Excel screen is a cell, and each cell can be located in a spreadsheet by means of its reference. Sometimes referred to as a cell address, a cell reference consists of the column letter and row number that intersect at the cell's location. For example, the cell in the top left corner of a spreadsheet has a cell reference of A1.
When cell references are used in formulas, Excel will calculate the answer using the data located in the referenced cells. If that data should later change, Excel will automatically recalculate the formula and update the answer.
Example:
Enter the following data into the listed cells:
C1: 5Enter the following formula into C3:
C2: 7
= C1 + C2
The answer 12 will appear in cell C3.
Change the data in the listed cells:
C1: 8
C2: 12
The answer in cell C3 will change from 12 to 20.
