Elapsed time
You start at 3:15 and play for 20 minutes. What time is it now?
Step 1 — within the same hour
If the minutes don't push past 60, just add:
3:15 + 20 min = 3:35.
Step 2 — crossing the hour
If you go past 60, you spill into the next hour.
3:50 + 20 min = ?
50 + 20 = 70 minutes.
70 minutes is 1 hour 10 minutes.
So 3:50 + 20 min = 4:10.
A reliable recipe
When the minutes go above 60:
- Add up the minutes: start_min + elapsed = total.
- Take how many whole hours are in total (divide by 60).
- The leftover is the new minutes.
7:45 + 35 min:
45 + 35 = 80 → 1 hour, 20 min over.
7 + 1 = 8 hours, 20 minutes → 8:20.
Working backwards
If a TV show started at 6:50 and lasted 40 minutes, when did it end?
- 50 + 40 = 90 → 1 hour 30 minutes.
- 6 + 1 = 7 hours, 30 minutes → 7:30.
Try it
Summary
- Add the minutes; if total > 60, carry into the next hour.
- 60 minutes = 1 hour.
- Practice catching the hour-rollover — that's where most mistakes hide.