What is SUM?
Adds all numbers in a range of cells. The most fundamental Excel function for calculating totals across rows, columns, or non-contiguous ranges.
Syntax
=SUM(number1, [number2], ...)
Example
Formula: =SUM(A1:A5)
Result: 15
How It Works
This formula adds all values in cells A1 through A5. If A1=1, A2=2, A3=3, A4=4, A5=5, the result would be 15. SUM ignores text values and empty cells, making it robust for mixed data ranges.