Formulas contain information to perform a numerical calculation such as adding, subtracting, or multiplying. All formulas must start with an equal sign (=), followed by:

Values or cell references joined by an operator. Example: =5+3 or =A1+A2.

A function name followed by parentheses containing function arguments. Functions are the most common way to enter formulas in Sheets. Example: =SUM(A1:A2).