Alohomora don't fail me now...
Needless to say... I went to get in my locker and didn't know the combination. My paper copy of the combination was in my wallet... that I had at the time of purchasing the combination lock. I upgraded to a new wallet and left the written copy in the old one. Oops.
I had an idea of the vicintity of the numbers. 11, 10, 5, 25, 20, 21... There wasn't anything above thirty or below five, but it left way too many variables. I tried and tried and tried. Stopped, went back out into the Black Friday madness... Thought some more.
I couldn't figure it out. I was tired being up for twenty four hours straight so far. Finally I just sat down and listened to the tumblers click and feel the lock shift. I managed to hit the right numbers and unlock my locker thankfully, without bolt cutters.