Using the time function for formulas.

Question

i am having alot of trouble adding when making my cells under the time format.  it comes up with crazy results.  i have made certain that the date is none and the time is uniform in all of the cells.  The table is entering under a time and having two separate exis.  it comes up with inconsitent answers.  i could convert all of the cells to a number format but that kind of defeats the purpose. 

Answer 1

The results aren't crazy.
You just fail to understand the app behavior.
There is no time values in Numbers, only date_time ones (+ duration ones in Numbers '09).
Those who took time to read Numbers User Guide know that there is always a date component in date_time cells.
Setting the date to none just tell the app that it must display only the time component.
If you enter the  value 2:30 on 2012/01/05 in B2, the cell will contain
2012/01/05 02:30:00 and will display 02:30:00
If you enter the  value 5:45 on 2012/01/20 in C2, the cell will contain
2012/01/20 05:45:00 and will display 05:45:00
If you want to make calculations upon what you are wanting to behave as time values, you must extract the time components.
For instance to get the difference between what are supposed to be time values in the two described cells
=TIMEVALUE(C2)-TIMEVALUE(B2)
But as is, you will get a value in decimal day.
To convert it in a classical date_time format you must use
=TIME(0,(TIMEVALUE(C2)-TIMEVALUE(B2))*24*60,0)
or, if thed values may embed seconds
=TIME(0,0,(TIMEVALUE(C2)-TIMEVALUE(B2))*24*60*60)
CAUTION, as it's clearly explained in the named resource,
the result will be the date_time value 1904/01/01 03:15:00
If you are sure that your document will not be used in Numbers '08, you may convert the result as a duration
=DURATION(,,,,(TIMEVALUE(C2)-TIMEVALUE(B2))*24*60*60)
CAUTION: you will have to define the duration format to display hours and minutes
I hope that this answer will convince you that you must read the User Guide.
Yvan KOENIG (VALLAURIS, France) mercredi 25 janvier 2012
iMac 21”5, i7, 2.8 GHz, 12 Gbytes, 1 Tbytes, mac OS X 10.6.8 and 10.7.2
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