time calculations

I am using excel to create a Timetable. I am running into a few problems. I need to use Universal Civil Time [incorrectly known as Military Time], which does away with the Colon and all the complex formulas by using the 24 Hour Clock that uses the numbers 0000 through 2359, and allows the use of 2400 as a substitute for 0000, and allows simple addition, subtraction, multiplication and division to do whatever math is required. All the program must be able to do is recognize the rollover from 59 to 00 at the end of every hour between 0000/2400 and 2359, and know how to introduce that rollover in math formulas.