• Q: Why life is complex?
  A: Because it has both real and imaginary components.

• "The number you have dialed is imaginary. Please, rotate your phone by 90 degrees and try again..."

• "In modern mathematics, algebra has become so important that numbers will soon only have symbolic meaning."

• Teacher: What is 2k + k?
  Student: 3000!

• Teacher: "Who can tell me what 7 times 6 is?"
  Student: "It's 42!"
  Teacher: "Very good! - And who can tell me what 6 times 7 is?"
  Same student: "It's 24!"

• Teacher: Do you have some questions about general calculus?
  Student: Is General Calculus a Roman war hero?

• Q: Why do you rarely find mathematicians spending time at the beach?
  A: Because they have sine and cosine to get a tan and don't need the sun!

• Theorem: Every positive integer is interesting.
  Proof. Assume towards a contradiction that there is an uninteresting positive integer. Then there must be a smallest uninteresting positive integer. But being the smallest uninteresting positive integer is interesting by itself. Contradiction!

• Theorem: Every positive integer is boring.
  Proof: Assume the contrary. Then there is a lowest non-boring positive integer. Who cares!

• Salary Theorem: The less you know, the more you make.
  Proof:
  Postulate 1: Knowledge is Power.
  Postulate 2: Time is Money.
  
  As every engineer knows: Power = Work / Time
  And since Knowledge = Power and Time = Money
  It is therefore true that Knowledge = Work / Money .
  Solving for Money, we get:
  Money = Work / Knowledge
  Thus, as Knowledge approaches zero, Money approaches infinity, regardless of the amount of Work done.

• A mathematician organizes a raffle in which the prize is an infinite amount of money paid over an infinite amount of time. Of course, with the promise of such a prize, his tickets sell like hot cake. When the winning ticket is drawn, and the jubilant winner comes to claim his prize, the mathematician explains the mode of payment: "1 dollar now, 1/2 dollar next week, 1/3 dollar the week after that..."

• A visitor at the Royal Tyrell Museum asks a museum employee: "Can you tell me how old the skeleton of that T-Rex is?"
  "It is precisely 60 million and three years, two months, and eighteen days old."
  "How can you know that with such precision?!"
  "Well, when I started working here, one of the scientists told me that the skeleton was 60 million years old - and that was precisely three years, two months, and eighteen days ago..."

• At a conference, a mathematician proves a theorem. Someone in the audience interrupts him: "That proof must be wrong - I have a counterexample to your theorem." The speaker replies: "I don't care - I have another proof for it."

• A mathematical biologist spends his vacation hiking in the Scottish highlands. One day, he encounters a shepherd with a large herd of sheep. One of these cuddly, woolly animals would make a great pet, he thinks... "How much for one of your sheep?" he asks the shepherd. "They aren't for sale", the shepherd replies. The math biologist ponders for a moment and then says: "I will give you the precise number of sheep in your herd without counting. If I'm right, don't you think that I deserve one of them as a reward?" The shepherd nods. The math biologist says: "387". The shepherd is silent for a while and then says: "You're right. I hate to loose any of my sheep, but I promised: One of them is yours. Have your pick!" The math biologist grabs one of the animals, puts it on his shoulders, and is about to march on, when the shepherd says: "Wait! I will tell you what your profession is, and if I'm right I'll get the animal back." "That's fair enough." "You must be a mathematical biologist." The man is stunned. "You're right. But how could you know?" "That's easy: You gave me the precise number of sheep without counting - and then you picked my dog..."

• The math professor just accepted a new position at a university in another city and has to move. He and his wife pack all their belongings into cardboard boxes and have them shipped off to their new home. To sort out some family matters, the wife stays behind for a few more days while her husband has already left for their new residence. The boxes arrive when the wife still hasn't rejoined her husband. When they talk on the phone in the evening, she asks him to count the boxes, just to make sure the movers didn't loose any of them. "Thirty nine boxes altogether", says the prof on the phone. "That can't be", the wife exclaims. "The movers picked up forty boxes at our old place." The prof 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 prof 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 prof says. "This is a cordless phone, so you can stay on the line and count with me: zero, one, two, three,..."

• Four friends have been doing really well in their calculus class: they have been getting top grades for their homework and on the midterm. So, when it's time for the final, they decide not to study on the weekend before, but to drive to another friend's birthday party in another city - even though the exam is scheduled for Monday morning. As it happens, they drink too much at the party, and on Monday morning, they are all hung over and oversleep. When they finally arrive on campus, the exam is already over. 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 backroads, 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:
  Problem 2 (95 points out of 100): Which tire went flat?

• Psychologists subject an engineer, a physicist, and a mathematician - a topologist, by the way - to an experiment: Each of them is locked in a room for a day - hungry, with a can of food, but without an opener; all they have is pencil and paper. At the end of the day, the psychologists open the engineer's room first. Pencil and paper are unused, but the walls of the room are covered with dents. The engineer is sitting on the floor and eating from the open can: He threw it against the walls until it cracked open. The physicist is next. The paper is covered with formulas, there is one dent in the wall, and the physicist is eating, too: He calculated how exactly to throw the can against the wall, so that it would crack open. When the psychologists open the mathematician's room, the paper is also full of formulas, the can is still closed, and the mathematician has disappeared. But there are strange noises coming from inside the can... Someone gets an opener and opens the can. The mathematician crawls out. "Damn! I got a sign wrong..."

• A physicist, a mathematician and a computer scientist discuss what is better: a wife or a girlfriend. The physicist: "A girlfriend. You still have freedom to experiment." The mathematician: "A wife. You have security." The computer scientist: "Both. When I'm not with my wife, she thinks I'm with my girlfriend. With my girlfriend it's vice versa. And I can be with my computer without anyone disturbing me..."

• After the phenomenal success of Viagra, Pfizer has come up with yet another pharmaceutical sensation: knowledge pills. A student who is way behind in his English literature class, goes to the pharmacy, and asks the pharmacist if there are knowledge pills for English literature. "Sure", the pharmacist replies. The student buys one, swallows it, and hours later he knows everything there is to know about English literature. If it's that easy to acquire knowledge, he thinks, why waste hours wrecking your brains over boring textbooks? So, he gives up studying, and whenever an exam is near, he goes to the pharmacy and buys the right knowledge pill: biology, art history, world history - you name it. When he has to take a math exam, he goes again to the pharmacy as asks for a knowledge pill for mathematics. "Just wait a moment", the pharmacist says. He disappears in the back of his store and comes back with a pill of the size of a melon. "But how am I supposed to swallow this?!" the student exclaims. "Well, math has always been a little hard to swallow..."

• The book Dynamic Programming by Richard Bellman is an important, pioneering work in which a group of problems is collected together at the end of some chapters under the heading "Exercises and Research Problems," with extremely trivial questions appearing in the midst of deep, unsolved problems. It is rumored that someone once asked Dr. Bellman how to tell the exercises apart from the research problems, and he replied: "If you can solve it, it is an exercise; otherwise it's a research problem." (Told by Donald E. Knuth in his book "The Art of Computer Programming")

• How mathematicians do it...
  
  Combinatorists do it as many ways as they can.
  Combinatorists do it discretely.
  (Logicians do it) or [not (logicians do it)].
  Logicians do it by symbolic manipulation.
  Algebraists do it in groups.
  Algebraists do it in a ring.
  Algebraists do it in a field.
  Analysts do it continuously.
  Real analysts do it almost everywhere.
  Pure mathematicians do it rigorously.
  Topologists do it openly.
  Topologists do it on rubber sheets.
  Dynamicists do it chaotically.
  Mathematicians do it forever if they can do one and can do one more.
  
  Cantor did it diagonally.
  Fermat tried to do it in the margin, but couldn't fit it in.
  Galois did it the night before.
  Möbius always does it on the same side.
  Markov does it in chains.
  Newton did it standing on the shoulders of giants.
  Turing did it but couldn't decide if he'd finished.
  

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Randomly picked up from the web. Thanks to the anonymous authors