use:

=Mod(B1-A1,1) to get value in column C

Format your Total cell as [hh]:mm:ss

"Leland7" wrote:

I have 2,300 entries of time. Column A is beginning time (23:30:48) and
Column B is ending time (01:18:24). I need to calculated elapsed time in
Column C and then add the sum of Column C to determine Average elapsed time
of the 2,300 entries. I have columns A B & C formated [h]:mm:ss. Problem is
fine until start before midnight and end after, the formula doesn't work.
Also, adding down column C for a grand total, doesn't work. Appears to not
want to go past 24.