Is there any way to make Excel show a negative time span? If I subtract two time values (say, when subtracting the actual amount of time spent on something from the amount of time planned for it) and the result is negative, Excel just fills the result cell with hashes to notify me that the result cannot be displayed as a time value. Even OpenOffice.org Calc and Google Spreadsheets can display negative time values. Is there a way to work around that issue by using conditional formatting? I really don't want to create some workaround by calculating the hours and minutes myself or anything like that.