What is IMSUM function in Excel? IMSUM function is one of Engineering functions in Microsoft Excel that returns the sum of two or more complex numbers in x + yi or x + yj text format. Syntax of IMSUM function IMSUM(inumber1, [inumber2], …) The IMSUM function syntax has the following arguments: Inumber1, [inumber2], … Inumber1 is required, subsequent numbers are not. 1…