Percentage display in a cell

I have an excel file, the cell data of a pivot table sheet in this file is calculated and populated following the formula: number * 100 in the data sheet, i.e. If the percentage is 2%, the value in the data sheet is 2. Now I meet problem when I try to display the percentage in pivot table. In format cells option, I chose Percentage (also chose "Sum" option in Summarize by field in Value Field Settings), and Excel will multiple cell values by 100 and display the result with a percent symbol, which is 200%. How to display the percentage correctly? I know one option is changing the data sheet formula from number * 100 to just display number. Is there any other easy option if it's hard for me to change the data sheet formula? Thanks.