HOW TO CONVERT EXCEL SHEETS TO PDF KEEPING THE CALCULATIONS?

Calculations done in Microsoft Excel will be lost when converting the spreadsheet file  to a PDF file.

The Microsoft Office family use Macro functions , such as some of your formulas in MS Excel.

These macros are developed with Visual Basic for Applications (VBA), a computer programmming language owned and developed by Micrososft, which also has become the standard accross all MS Office programs.

Even though you can implement JavaScript for MS Office using some very complicated frameworks, the same is not true with VBA; it is exclusive to MS Office.

In the same context, Acrobat JavaScript is exclusive to the Adobe Acrobat program; as indicated by Bernd Alheit, you must manually develop the script(s) that would calculate in the same way as  the  macros used in your spreadsheet but using Acrobat JavaScript.

Convert the file into PDF and add the calculations in Adobe Acrobat.