In the dusty street of an Old West mining town, a classics professor was stunned to find a post bearing this inscription:
TOTI EHORS ESTO
What was the post for?
In the dusty street of an Old West mining town, a classics professor was stunned to find a post bearing this inscription:
TOTI EHORS ESTO
What was the post for?
If you start at the North Pole and walk one mile south, one mile east, and one mile north, you’ll find yourself back at your starting point.
The North Pole is not the only point with this property on Earth’s surface. In fact, there are any number of such points. Where are they?
I am greater than God, and more evil than the devil. Poor people have me. Rich people want me. And if you eat me, you’ll die. What am I?
Suppose you put a coin into an empty bottle and then insert a cork in the bottle’s opening. How could you retrieve the coin without breaking the bottle or pulling out the cork?
Another puzzle from Henry Ernest Dudeney:
“In the illustration Professor Rackbrane is seen demonstrating one of the little posers with which he is accustomed to entertain his class. He believes that by taking his pupils off the beaten tracks he is the better able to secure their attention, and to induce original and ingenious methods of thought. He has, it will be seen, just shown how four 5’s may be written with simple arithmetical signs so as to represent 100. Every juvenile reader will see at a glance that his example is quite correct. Now, what he wants you to do is this: Arrange four 7’s (neither more nor less) with arithmetical signs so that they shall represent 100. If he had said we were to use four 9’s we might at once have written 99 9/9, but the four 7’s call for rather more ingenuity. Can you discover the little trick?”
How can you put 10 lumps of sugar into three cups so there is an odd number of lumps in each cup?
In old Konigsberg there were seven bridges:
Villagers used to wonder: Is it possible to leave your door, walk through the town, and return home having crossed each bridge exactly once?
Swiss mathematician Leonhard Euler had to invent graph theory to answer the question rigorously, but there’s a fairly intuitive informal proof. Can you find it?
The following riddles have the same answer. What is it?
Another puzzle from Henry Ernest Dudeney:
“Here is a curious mechanical puzzle that was given to me some years ago, but I cannot say who first invented it. It consists of two solid blocks of wood securely dovetailed together. On the other two vertical sides that are not visible the appearance is precisely the same as on those shown. How were the pieces put together?”