Another joke about engineers

A journalist, a mathematician, a physicist and an engineer were having dinner together.

"I've heard it proposed," said the journalist, "that all odd numbers are prime."

"Let me see," said the mathematician. "One is prime, three is prime, five is prime, seven is prime." I suppose by a process of mathematical induction we might be able to prove that all odd numbers are prime.

"Hmm," said the physicist. "One is prime. Thirteen is prime. 47 is prime. Eleven is prime. 9 is not prime, but that could be experimental error. I suppose we could sample the universe of odd numbers and determine whether this is true."

"Well," said the engineer, "One's prime, three's prime. Hell, they're all prime."