Relax! This happens to many TAs during the first discussion session. Luckily, you are pretty sure of the first number, which will at least get you on the correct floor. However, you can’t remember the order of the last two digits. Is it 324 or 342? So, you wait 5 minutes in room 324 and see if any students show up. No one does, so you go to 342 and wait again. Unfortunately, no one is there either. So, you begin to check all the rooms on that floor and you finally find your class in 334.
Scenario 3: Stop running!