you need to protect the worksheet. in the protect options, you can unclick the default checked options that allow users to select protected cells. therefore, they'll be able to see the output, but cannot put the cursor over the cells with formulas in them to steal the base formula, edit it, etc. that will also prevent them from copy and pasting in to a new workbook.
i spend 8-10 hours a day in excel, so hit me up if you have any other questions. /excel nerd.