Excel formulas for beginners. SUM() function is used to add or sum numbers in excel. Ex. see on video. Formula: =SUM(cell range/cell address/number1, number2...) Example: =SUM(B2:B13) --cell range =SUM(B2,b5,b9) --Cell address =SUM(10+20+50) --Numbers Description: SUM: - Function (formula) B2,B13.....: - Cell Address : :- Indicate the range of cells.