Bug associated with how ISNUMBER handles blank cells when used in SUMPRODUCT
With the help of a user who is using Excel 15.25 on a Mac, we discovered a difference between how ISNUMBER handles blank cells when used within the SUMPRODUCT formula. Or at least that is what we think is going on. I am using Excel 2016 on a PC. I have attached a test workbook, a screenshot of what I see when I open the workbook in Excel 2016 on a PC, and what the user see when he opens the same workbook in Excel 2016 on a Mac.
If A1 is a blank cell, then ISNUMBER(A1) returns FALSE.
So, you would think that if the range C3:J3 contained two cells with numbers and the other 6 cells were blank, the following function should return the value of 2: =SUMPRODUCT(1*ISNUMBER(C3:J3))
But, it looks like ISNUMBER is returning TRUE for blank cells when used within SUMPRODUCT this way.