time and date calculator

[chiphead]

is there a handheld calculator on the market that lets you input a date and time,add or subtract a set amount of hours (eg 96 hours) and gives you the answer in the same format i.e date and time.

[smouse]

If you know how you can use Microsoft Excel for such calculations and a number of hand-held devices have Windows on these days. 

 

I've never seen any calculators that can do this though subtracting 96 hours is like subtracting 4 days but I guess you would be doing more complex calculations than this.

[Pinotage]

Any handhold with a programming language would give you this facility, but you -or someone- would have to write a program to do the calculation.