PURPOSE Formulas calculate values automatically in a spreadsheet. COMMON FORMULAS Use addition, subtraction, multiplication, division, SUM, AVERAGE, MIN, MAX, and COUNT for basic calculations. HOW FORMULAS WORK Most formulas begin with an equals sign and refer to cells or ranges. BEST PRACTICES Use cell references instead of typing numbers directly into formulas when possible. This makes the sheet easier to update. CHECK Test formulas with simple examples before copying them across a large range.