subtracting dates and times in Excel

[bdjb]

Hello,
I have a "last modified date and time" and I would like to be able to subtract it from the current date/time to get an amount of time since the last modification. When I try to just subtract the cells, I get the error #value.
Anyone have an idea of a formula that would work?

Thank you very much,
Bob

 

[xlbo]

If Last Modified date and time is in A1 then
=Now()-A1
will work
Rgds
Geoff
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