how to write formulas in spreadsheets

To write a spreadsheet formula, select a cell, type an equals sign (=), and enter your calculation using cell references, operators, or functions.

Start with an equals sign. Every formula must begin with an equals sign (=). Without it, the spreadsheet will treat your entry as plain text.
Use cell references. Use cell references (e.g., A1, B2) instead of hardcoded numbers so that your results update automatically whenever the underlying data changes.
Incorporate functions. Functions are predefined formulas that simplify complex tasks. Type the function name followed by its arguments in parentheses, such as =SUM(A1:A10).
Copy formulas efficiently. If you need to apply a formula to multiple cells, you can use features like drag-fill, auto-fill, or copy-paste to quickly propagate the calculation.