1. Open Microsoft Excel and create a blank spreadsheet, if one doesn't open automatically.
2. Double-click in the cell that you want to create a random number in.
3. Type '=Rand()*(b-a) a' (without quotes) to create a random number between and including the smallest number 'a,' and the largest number 'b.' For instance, if you want to create a cell that displays a random number between 0 and 100 every time you recalculate the spreadsheet, you'd type '=Rand()*(100-0) 0.' This number can then be used in other calculations throughout the sheet, in order to test how certain functions respond to randomly generated values.