"Monkey business" implies mimicry. If there is a mirror in the room, the safe combination might be the reverse of another number written on the wall.
The puzzle is designed to make you laugh at yourself. While you are calculating prime numbers, the answer is usually the silliest thing in the room. Look for a crayon drawing of a banana, look for the number of fingers on a statue, or simply input 0000 . monkey business safe combination
When in doubt, remember the infinite monkey theorem: If you spin the dial enough times, you will eventually hit the right number. "Monkey business" implies mimicry
