Syntax: @SUM(argumentlist)
argumentlist = any combination of numbers, cells, or ranges
@SUM returns the sum of its arguments. Blank cells and cells containing strings are not counted.
Examples:
@SUM(10, 20, 30, 40, 50) = 150
@SUM(L1..L3) = 15.10564, where L1 = 1.32342, L2 = 5.45735, and L3 = 8.32487
@SUM(A1, B1, C1, D1) = 0, where A1 = -1, B1 = -9, C1 = 9, and D1 = 1