You're better off to write your own spreadsheet. The only way to verify the correctness of a spreadsheet is to verify each equation. A difficult task with excel as the formulations are so cryptic, as compared to mathcad, for instance. It is folly to think you can verify a spreadsheet, or any software, for that matter, by running a few example problems. By the time you're done deciphering the formulas in excel, you can write your own spreadsheet.