Mental Patient’s Exit Exam

Three guys go through an exit interview at a mental hospital. The doctor says he can release them if they can answer the simple mathematical problem: “What is 8 times 5?”

The first patient says,
The second one says,
The third says,
What a stupid question. It's obvious: The answer is 40.

The doctor is delighted. He gives the third guy his release. As the man is leaving, the doctor asks how he came up with the correct answer so quickly.

It was easy, Doc. I just divided Wednesday into 139.