11,388
You should get an hour to two hours of exercise a day if you are 13 years old.
56 days and 13 hours.
At least 10
Either as much as you want or.. 13 hours
Just multiply the number of years (13) times the number of days in a year (365) times the number of hours in a day (24).
There are (13 + 24k) hours where k is an integer.
13 seconds is 0.0036 hours.
13 to 13 and 1/2 hours
13 hours
13 hours
13 hours.