Subtracting Times producing negative numbers

[doug.sloane]

I have 2 columns with times in them in a HH:MM format.I'm trying to subtract them from each other but when the column I'm subtracting is greater than the column being subtracted form I get garbage as the result. I can understand why negative time is a problem in a quantum physics sense (or maybe not) but why is it a problem to show a negative HH:MM ???? I could do it with a big long macro / formula with mod 60 for minutes and mod 24 for hours but don't want to. Is there an easier way ?

 

[Juan Pablo González]

Use the 1904 date system.