What is SUMSQ function in Excel? SUMSQ function is one of the Math and Trig functions in Microsoft Excel that returns the sum of the squares of the arguments. Syntax of SUMSQ function SUMSQ(number1, [number2], …) The SUMSQ function syntax has the following arguments: Number1, number2, …    Number1 is required, subsequent numbers are optional. 1 to 255 […]