me in class: ok, so class lasts 2 hours, so i have to wait 1 hour twice, or 30 mins 4 times, or 20 mins 6 times, or 15 mins 8 times, or 10 mins 12 times, or 5 mins 24 times, or 2.5 mins 48 times, or 2 mins 60 times, or 1 min 120 times, or 30 secs 240 times