If you use the 1904 date system in excel, you can use negative time
(tools=options=calculate tab).

However, this will probably make all your dates off by 4 years.

If you want to use decimal number of hours you can

=(a1-a2)*24

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Regards,
Tom Ogilvy

"André Lavoie" wrote in message
.. .
Would like to cumulate work time in a schedule. I have to compare worked
time to a maximun dayly working time of 7:00 hours. so if I worked 5 hours
out of 7 I would like to obtain minus 2 hours (-2:00) I tried a1-a2
format
to day and time... No succes

Any ideas ???

André Lavoie