Format cell to allow input as negative time-value

[blaksnm]

Hey guys
I try to make a summary of a set of timevalues (tt:mm) - some of the values are less than zero. What format will allow Excel to summarize and handle such negative timevalues
Hopefully one of you guys will guide me
I use MS 2007

 

[RichardMGreen]

As far as I know, Excel can't handle negative time without some sort of intermediate step.
...... At least I've never been able to get it to, all I get is a load of #'s.

 

[blaksnm]

Oki doki - thanks for your answer though
Have a nice weekend

 

[barry houdini]

You can use negative time if you use "1904 date system"

To set this...

Office button at top left > Excel Options > Advanced > Scroll down to "When calculating this workbook" and tick "Use 1904 date system"

see also this Microsoft link on the subject

Note that changing to 1904 date system in an existing worksheet will alter existing dates.....

 

[blaksnm]

Thanks!