the time in the top window. You first enter a time in 24 hour format For example 6:12:0 which is read as 6 hours 12 minutes and zero seconds. (6:12 am). After that you enter durations and add/subtract them from the time in the top window.
Enter a time in three parts: the hours in left field, minutes in the middle, and seconds in the right field. When entering a time, the calculator checks that the hours are in the range 0-23, minutes and seconds are in the range 0-59.
Enter the time by pressing "Enter a time". The time is placed in the top window, replacing what was there.
Enter a duration in the the three input boxes. The inputs can be any positive number. For example you could enter 100 in the minutes box and press "+". This would add 100 minutes to the time and display
