How to add times (HH:mm) or (HH:mm:ss) in a regular calculator

Ever so often, I have been wanting to add times in a regular calculator. Thanks to a friend of mine (ISP), and some improvisation, here's the technique.

In case of adding two times, lets say, 1:36 and 2:40 - replace the ":" with a 0 in the calculator and add the times. This will give you 1036+2040=3076. Now, resolve by replacing the middle 0 with ":". In case this yields in a minutes figure of more than 60 (which is the case here), add 940 until you get an acceptable figure in the minutes/seconds figure. So 3076+940=4016. Your answer is 4:16.

In case of subtraction, you will need to keep subtracting 940 from the answer till you get an acceptable value.

Hope this helps.