Sums the contents of cells.
SUM(number1, number2, ... number30)
number1 to number30 are up to 30 numbers or ranges/arrays of numbers whose sum is to be calculated.
SUM ignores any text or empty cell within a range or array.
SUM can also be used to sum or count cells where a specified condition is true.
SUM(2, 3, 4)
returns 9, because 2+3+4 = 9.
(where cells B1, B2, B3 contain 1.1, 2.2, 3.3) returns 6.6.