Subtracting Dates to Show Hours Spanning Multiple Days

Hi all,

As it says above really; I am looking for a way to subtract date time stamps and show the result in hh:mm:ss.

COLUMN A COLUMN B COLUMN C
01/01/2016 10:10:53 05/01/2016 11:49:25 =B1-B2

In C1 I get 01:38:32.

C1 is formatted to show hh:mm:ss -- so it is doing the calculation right.
If I change the format of the cell to dd/mm/yyyy hh:mm:ss; the result in C1 is now 04/01/1990 01:38:32

So, how do I make it perform the deduction and show 97:38:32 ??

I have tried converting to days, subtracting and *24 then adding to time; but (1) its ugly and messy & (2) it falls down at the end of a calendar month/year and gets even uglier and messier.

Any help greatly appreciated

Cheers

Andy

Format as

[h]:mm:ss

Both, thanks very very much.