A formula turns a cell from a fixed number into a calculated result — the whole reason Excel exists rather than a plain table in Word.
Every formula begins with an equals sign. =A1+B1 adds the values currently in those two cells — and updates automatically if either one changes.
| Operator | Does |
|---|---|
| + | Add |
| - | Subtract |
| * | Multiply |
| / | Divide |
=SUM(A1:A10) adds every cell in that range. =AVERAGE(A1:A10) finds the mean. Both are far faster and less error-prone than adding a long column by hand.
Excel formulas follow the same order of operations as regular math — multiplication and division happen before addition and subtraction. =2+3*4 gives 14, not 20. Use parentheses to force a different order: =(2+3)*4 gives 20.