Convert Formula to Value

I'm new to Perl, but I need to use it to write into an excel spreadsheet. I want to copy the values of certain cells into a new sheet in the workbook. I'm unsure of how to do this because I don't know how to copy values instead of formulas.

Note: by formula I mean '=SUM(A1,A2)' and by value I mean A3 (where A3 = A1+A2)

Any help would be greatly appreciated.