
07/06/2004, 08:43 AM
#1
Does anybody like brainteasers? Here is one of my favourites:
When Albert Einstein already was quite a famous Professor in Zurich, he got on a tram with a friend of his. The conductor, who liked brainteasers, knew Einstein and asked him the following question: "How many times per day is it possible to exchange (mentally) the hour hand and the minute hand of a clock, and again get a possible alignment of the hands (an alignment that shows a feasible position of the hands)?"
Einstein continued his ride on the tram and the discussion with his friend, but when they got off, he gave the conductor the correct answer, also telling him he would have to wait for the proof until the next day.
So the question is: "How many times per day is it possible to exchange (mentally) the hour hand and the minute hand of a clock, and again get a possible alignment of the hands (an alignment that shows a feasible position of the hands)?"
Here a few hints:
 No, this is not a trick question
 It is more than 100 but less than 1000 times per day
 You can solve it on the back of an envelope (if you look at the problem the right way), no computer or complex mathematics needed...
Looking forward to answers (or other brainteasers), ready, steady, go...


