a night Watchman must check a certain stores are every 45 minutes if he first checks the area as he begins a 9-hour of Duty how many times will he have checked this storage area.

Question

I got 12 the the answer say its 13 times he will check

Answer 1

there's a check at the start and at the end.
There are 12 checks after the start of the shift. But you need to count the check at time zero as well.