Adding Beyond 24 Hours
You can add times by using the SUM function (or a simple plus sign). Therefore, =SUM(A1:A5) would result in Total Hours if A1:A5 contained valid times. Excel will not add past 24 hours. This is because when a time value exceeds 24 hours (a true value of 1), it rolls into a newday and starts again. To force Excel not to default back to a newday after 24 hours, you can use a cell format of 37:30:55 or a custom format of [h]:mm:ss.
You can use a similar format to get the total minutes or seconds of a time. To get the total minutes of the time 24:00, for instance, format the cell as [m] and you will get 1440. To get the total seconds, use a custom format of [s] and you get 86400.
