[iPhone God App] It was found using the time:calc actually

time:calc 3 for iPad and iPhone is a calculator that works in time - this is ideal for calculating working hours, quoting for jobs, flight times, cooking times etc. It’s also ideal for video and film editors as it can work in standard and custom timecode modes.

If you want to calculate your working hours and you started work at 9:08 and finished at 11:53, then type in 11:53 - 9:08. time:calc will tell you that you have worked 2 hours 45 minutes.

If you are editing video need to know 18:23:32:18 + 8 minutes 3 seconds and 12 frames, simply type 18:23:32:18 + 8:03:12 and time:calc will tell you to look at 18:31:36:05 (in this case working at 25FPS). Industry standard and custom frame rates are supported. Memory keys are also handy if you are working with constant offsets and timings.