What was initially posted is a math problem, pure and simple. It has nothing to do whatsoever with the ‘date/time’ data type. Gotta say that I’m disappointed with the veteran posters who got sucked into this and proceeded to reinforce the relative inexperienced programmer’s misconceptions about date/time data type (which is all about actual dates/times) and encouraged him to continue to use it versus concentrating on elapsed times, which is all about adding (as integers) days, hours, minutes and seconds.
Given the guidance provided, the poster is on a slippery slide to disaster.
How about regrouping and talking about:
(a) Converting a string representation of minutes (e.g.” 07”) to seconds (i.e. 420)
(b) Formatting an integer to a string value, (e.g. 426 = “07:06”)