Teach Excel demonstrates how to change the columns from letters to numbers in Excel 2007. The first step is to click on the Office button in the top left part of the window. Next, you click on Excel Options and click on the Formulas tab. There should be a heading labeled "Working with Formulas." The checkbox for R1C1 reference style should be unchecked by default. Check that box and click OK. This changes the column headers from letters to numbers. In order to change back to letters, simply go back to Excel Options window and click the Formulas tab. Unchecking the R1C1 reference style box will bring the columns back to normal.