If a plane departs at 7:44 P. M. and arrives at 11:15 P. M., what was the length of time for the flight?

Well, that's quite easy and there are a few ways to count it. I would do it like this:

- Find the difference between 11:00 p. m. and 8.00 p. m. - it's 3 hours.

- Add 16 minutes (because there's still difference between 7:44 and 8:00)

- Add 15 minutes (because there's still difference between 11:15 and 11:00)

The result is: 3 hours + 16 minutes + 15 minutes = 3 hours and 31 minutes. And that's how long the flight took.