What are the classic jokes in the field of mathematics?

A mathematician went to look for a job. The interviewer asked him, "What would you do if you suddenly saw a building on fire and many people were asking for help on your way to the company to attend an important meeting?" . The mathematician said, "Life is much more important than meeting. I will call the fire brigade immediately and try my best to help the trapped people. " . The interviewer was satisfied with this answer, so he went on to ask the last question, "What if the building didn't catch fire?" . The mathematician thought for a moment and said confidently, "I will set fire to the building, so that I can simplify one problem into another that has been solved!" " "