An hour has 60 minutes, so.. approx. 86609,5 hours. Let's say it's 86610 hours.
Use a calculator.
0 hours are in 20 min an hour is 60 min
8 hours, 20 minutes
610 min / 60 = 10.167 hours.
5 hours, 50 minutes
2 hours
3 hours
2 hours
1.95 hours.
5.5 hours.
13 hrs.
320 min = 51/3 hours = 5hours 20minutes
157 minutes