How to Do the Sum of an Indefinite Series in Excel. The Microsoft Excel program includes a variety of mathematical formulas that you can apply to any cell in a spreadsheet.

You can sum a series of numbers in Microsoft Excel manually by typing in a simple formula, or automatically with a tool.

Although a running balance is commonly maintained on the same Excel worksheet as the debits or credits, you can also keep a running balance with figures that reside on different Excel sheets.