How to Change Positive Data to Negative on Microsoft Excel

1. Click 'Start,' 'All Programs,' 'Microsoft Office' and then 'Microsoft Excel 2010.' Click 'File' and 'Open.' Locate your file and click 'Open.'
2. Double-click the cell containing the number you wish to change from positive to negative. Enter the negative symbol before the first number and press 'Enter.'
3. Select 'Number' from the drop-down list in the Number group of the Home tab of the ribbon bar. Click the expander arrow in the lower right of the Number group or 'Alt,' 'H,' 'F' then 'M' to show all the formatting options.
4. Select one of four options for displaying negative numbers on the Number tab. Click 'OK.'
5. Click 'Conditional Formatting' > 'Highlight Cell Rules' > 'Less Than' to set conditional formatting. Enter '0' (zero) in the first box and select an option from the second. Click 'OK.'