Yeah... I think it is interesting. At first I thought it could be done with
sheet functions, putting intermediate results in different columns but that
didn't work for me.

.. IMHO I'm pretty sure Anands' best solution is to write a function. From
your answer I think we are on the same page.

There are 3 bits I reckon... Change the given text to a reconisable
date/time... Do the arithmetic... Change the answer back to a recognisable
format... I think.

Same as you... I also did the seperation into 3 sets of 2 characters but I
used the MID() function for all of them rather than LEFT() MID() RIGHT().

The last number given though "11600" prompted my questions. You've "solved"
them by saying ok.. Drop the leading zero if it's earlier than 10 o-clock
'cause it’s a number!!!!

Brilliant!!! And soooo obvious I of course missed it.

I still don't see how to take account od say... 28 hours difference  though.