- number1 – The first item to sum.
- number2 – [optional] The second item to sum.
- number3 – [optional] The third item to sum.
The SUM function sums values supplied as arguments (up to 255 arguments).
Arguments can be supplied as numbers, cell references, ranges, arrays, constants, and the results of other formulas or functions.
For example, SUM(C1:C3) adds all the numbers that are contained in cells C1 through C3, which is equivalent to SUM (C1, C2, C3)