What does it mean to number format and why format numbers at all?

By default, each cell in Excel is formatted as "General" which means that the cell has no formatting rules. In order to have numbers appear consistently throughout your spreadsheet, it is helpful to tell Excel what type of number you are inputting, i.e. format the number.

Excel has several different types of number formats such as currency, time, dates, and phone numbers. Try using the different number formats to give your spreadsheets a consistent look and feel.