A professor applies for a job as a plumber.

A professor of mathematics discovered a leak in his home's kitchen sink. He made a phone call to a plumber. The plumber arrived the next day, tightened a few screws, and everything was back to normal.

The professor was quite pleased. He was taken aback when the plumber handed him the bill a minute later. He said, "This is one-third of my monthly pay!"

Regardless, he paid it, and the plumber then replied to him, "As a professor, I understand your stance. Why don't you apply for a plumber employment at our company? You'll make three times what a professor does. But keep in mind that when you apply, you must state that you have only finished seven elementary classes. They despise educated individuals."

So that's what occurred. When the professor acquired a job as a plumber, his life changed dramatically. He only had to seal a few screws now and then, and his pay increased dramatically.

The board of the plumbing firm decided one day that every plumber would have to attend evening classes to finish eighth grade. As a result, our lecturer had to accompany us. It just so happened that math was the first class. To test students' understanding, the evening teacher asked for a formula for the area of a circle. The professor was the one who inquired. He dashed to the board, only to discover that he had forgotten the formula. He began to reason about it, filling the white board with integrals, differentials, and other difficult formulas in order to arrive at the answer he had forgotten. He got "minus pi times r square" as a result.

He didn’t like the minus, so he started all over again. He got the minus again. No matter how many times he tried, he always got a minus. He was frustrated.

He looked a bit scared at the class and saw all the plumbers whisper:

“Switch the limits of the integral!!!”

He shouted, "This is one-third of my monthly pay!"