I understand why this is wrong (order of operations dictates the division happens first, so it's really 25 - 1 = 24), but why is it funny? I don't mean "This isn't funny," I think I'm just missing the joke.
The exclamation point makes it right. The formula, when worked with proper order of operations, equals 24, which is equal to 4 factorial (4!) 123*4=24