=IF(MOD(A1,1)=0,TEXT(A1-1,"dd mmm yy")&" 24:00",A1) but of course you
couldn't use the result in calculation as it is a text string, not a number.

As a matter of interest, how did you format the cell to show "10th Mar"?
Any answers which I have seen to the "st, nd, rd, th" question have involved
converting to a text string, rather than formatting.
--
David Biddulph

"sorab" wrote in message
...
Hi, I'd appreciate a solution if any to my query.
I have entered a date and time in a cell as (9mar09 24:00)
The cell is formatted to show date and time and it correctly reads it
as 10th Mar 09 00:00.
However I want the cell to show me 9th Mar 09 24:00, which is really
the same time.
It is not happening, is this possible to do, appreciate your help.
Sorab