If you follow the logic of your formula, two blank cells 'equal' each
other. Your formula says that if c10 is NOT greater than b10 (which
being equal matches) then subtract the difference (in this case, zero)
from 1, which leaves 1, which Excel interprets as 24:00 in time
format.

Therefore, you need to exclude the situation where both values are
equal, such as:

=if(c10=b10,"",if(c10b10,c10-b10,1-(b10-c10))) or
=if(c10=b10,0,if(c10b10,c10-b10,1-(b10-c10)))

Does this work for you?

Bruce


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swatsp0p


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