"There were thousands of possible combinations"
There were 5 letters to pick from. Assuming that no letter is used twice (which is in fact the case and the way a normal person would do it), that means there's 5! combinations to pick from. That's only 120 combos! And assuming that you recognize 212 as boiling point in F, that goes down to 60. (The 0 may throw you off, being both absolute 0 in k and freezing point in C, and 33 being closeish to freezing in F.)
Including every possible combination is only 3125, which would take about 52 minutes at 1 combo/second, probably closer to an hour to compensate for distraction and repeated combos.
I actually never pronounce words in my own game.