**I haven't invented these jokes - I just collect them.**Q: Why did the topologist's marriage fail?

A: Because he thought that arbitrary unions were open.

*k*+

*k*?

Student: 3000!

A: Pumpkin Pi!

A: A high school math problem!

Student: "It's 42!"

Teacher: "Very good! - And who can tell me what 6 times 7 is?"

Same student: "It's 24!"

A: You say: "Your brain is smaller than any ε>0!"

"Thirty nine boxes altogether", says the professor on the phone.

"That can't be", the wife exclaims. "The movers picked up forty boxes at our old place."

The professor counts once again, but again his count only reaches 39. The next morning, the wife calls the moving company and complains. The company promises to check; a few hours later, someone calls back and reports that all forty boxes did arrive. In the evening, when the professor and his wife are on the phone again, she asks: "I don't understand it. When you count, you get 39, and when they do, they get 40. That's more than strange..."

"Well", the professor says. "This is a cordless phone, so you can stay on the line and count with me: zero, one, two, three,..."

A: A large pizza can feed a family of four...

*New York*

*(CNN)*: At John F. Kennedy International Airport today, a Caucasian male (later discovered to be a high school mathematics teacher) was arrested trying to board a flight while in possession of a compass, a protractor and a graphical calculator.

According to law enforcement officials, he is believed to have ties to the Al-Gebra network. He will be charged with carrying weapons of math instruction.

The pure mathematician: "Would 30,000 € be too much?"

The applied mathematician: "I think 60,000 € would be OK."

The math finance person: "What about 300,000 €?"

The personnel officer is flabbergasted: "Do you know that we have a graduate in pure mathematics who is willing to do the same work for a tenth of what you are demanding!?"

"Well, I thought of 135,000 € for me, 135,000 € for you - and 30,000 € for the pure mathematician who will do the work."

A: `Paper or plastic?'

- A mathematician: "Pi is the ratio of the circumference of a circle to its diameter."
- A computer programmer: "Pi is 3.141592653589 in double precision."
- A physicist: "Pi is 3.14159 plus or minus 0.000005."
- An engineer: "Pi is about 22/7."
- A nutritionist: "Pie is a healthy and delicious dessert!"

A: Prime Rib!

They go to the professor's office and offer him an explanation: "We went to our friend's birthday party, and when we were driving back home very early on Monday morning, we suddenly had a flat tire. We had no spare one, and since we were driving on back roads, it took hours until we got help."

The professor nods sympathetically and says: "I see that it was not your fault. I will allow you to make up for the missed exam tomorrow morning."

When they arrive early on Tuesday morning, the students are put by the professor in a large lecture hall and are seated so far apart from each other that, even if they tried, they had no chance to cheat. The exam booklets are already in place, and confidently, the students start writing.

The first question - five points out of one hundred - is a simple exercise in integration, and all four finish it within ten minutes.

When the first of them has completed the problem, he turns over the page of the exam booklet and reads on the next one:

*Which tire went flat?*

*2 * 2*.

The applied mathematician's solution: We have: \[2*2=2*\frac{1}{1-\frac{1}{2}}\] The second factor on the right hand side has a geometric series expansion : \[\frac{1}{1-\frac{1}{2}}=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\cdots \] Cutting off the series after the second term yields the approximate: \[2*2=2*\left ( 1+\frac{1}{2} \right )=3\] | The pure mathematician's solution: We have: \[2*2=(-2)*\frac{1}{1-\frac{3}{2}}\] The second factor on the right hand side has a geometric series expansion: \[\frac{1}{1-\frac{3}{2}}=1+\frac{3}{2}+\frac{9}{4}+\frac{27}{8}+\cdots \] which diverges. Hence, the solution to $2*2$ does not exist. |

A: A person who cannot tell a doughnut from a coffee mug.

A: Man faltet, um zu glätten...

*The pun only works in German.*