To get 24:00 displayed, you need a format of [hh]:mm, not hh:mm.

However, I doubt that's your problem. To get the results you are showing,
someone must have entered 24, as opposed to 24:00, which Excel interpreted
as 24 days, rather than 24 hours. Correct the data entry, and you should be
fine.

Regards,
Fred.

"The Mysterious J" wrote in
message ...
In some worksheets, a cell formatted hh:mm with a value of 24 will yield
the
desired result - 24:00 (24 hours). As of today some worksheets are
yielding
00:00 for the same value of 24, and in the formula bar, you can see that
the
24 has been converted to 1/24/1900 12:00:00AM - the 24th day of the
century.
How can this be corrected so that it will show 24 hours.