Mr. Bean: Are you trying to fool me, you've just twisted the figure, the answer is 6!!
Counting The Boxes
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,..."
A math professor is lecturing through a rather long and complicated proof. At one point he says, "It is obvious that equation 32 follows from 31."
A student towards the back of the lecture hall asks, "How is that obvious?"
The professor looks back at the blackboard, starts to speak, but then remains silent as a consternated look falls across his face. After ten minutes of silent pondering, he erases three blackboards and manically fills them with equations, derivations, and other expressions. After another half-hour of furious scribbling--eventually filling both sides of two more free-standing chalkboards--he exclaims, "AHA! It is obvious!"
Trying To Impress
A teacher was trying to impress her students with the fact that terms cannot be
subtracted from one another unless they are like terms. "For example," she continued, "we cannot take five apples from six bananas."
"Well," countered a pupil, "can't we take five apples from three trees?"