“A dirigible took off from Leningrad in a northerly direction. Five hundred km away it turned and flew 500 km eastward. After that it turned south and covered another 500 km. Then, it flew 500 km in a westerly direction, and landed. The question is: where did it land: west, east, north, or south of Leningrad?”
“That’s an easy one,” someone said. “Five hundred steps forward, 500 to the right, 500 back and 500 to the left, and you are naturally back, where you had started from!”
“Easy! Well then, where did the dirigible land?”
“In Leningrad, of course. Where else?”
“Wrong!”
“Then, I don’t understand.”
“Yes, there is some catch to this puzzle,” another joined in. “Didn’t the dirigible land in Leningrad?”
“Won’t you repeat your problem?”
The flier did. The listeners looked at each other.
“All right,” the professor said. “We have enough time to think about the answer. Let’s have the next now.”
Cheers,
Nalin Pithwa
Mathematics Hothouse 