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Answers: You can view many teasers and riddles at http://www.mindchallenger.com

Here is one for you to try before going there and looking for the answer:

Three masters of logic wanted to find out who was the wisest one. So they invited the grand master, who took them into a dark room and said: "I will paint each one of you a red or a blue dot on your forehead. When you walk out and you see at least one red point, raise your hands. The one who says what colour is the dot on his own forehead first, wins." Then he painted only red dots on every one. When they went out everybody had their hands up and after a while one of them said: "I have a red dot on my head."
How could he be so sure?

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Let's call the monk who raised his hand Bob, and the other 2 Joe and Steve. Bob first assumes that his dot is blue. He can see that Joe and Steve have red dots, and have raised their hands - but neither of them spoke up.

If Joe and Steve were looking at a blue dot on Bob's head, and they saw all 3 hands raised, then they should both know that they have red dots. Example: Joe would raise his hand since he saw Steve's red dot. Bob would also raise his hand for the same reason. Steve also has his hand raised, so Joe should know that Steve is looking at a red dot on Joe's head.

Since neither of them spoke up, that means that they are looking at a red dot on Bob's head. Bob was the first one to figure it out.

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The monk saw everyone else's hands raised, and he saw only red dots, so he raised his hand as well. Therefore, since everyone had a raised hand, he knew he must have a red dot. If he saw someone who didn't have a raised hand, someone would have a blue dot. Since he didn't see anybody that did not raise his or her hand and he only saw red dots, he could safely assume that they all had red dots. I don't think it took a lot of brainpower, just patience.

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1. he looks in a mirror
2. sum1 else tells him

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There is no way the monk could tell he had a red dot unless he exited the room first or second and the monks raised their hand the moment they saw a red dot. Then it would come down to who spoke first.
To elaborate, Monk #1 comes out, sees nothing. Monk #2 comes out, sees the red dot on #1's forehead, and raises his hand. #1 sees the red dot on #2's forehead and raises his hand. At this point they would both know that each had a red dot, but being polite they wait for #3, who has no way of telling if his dot is red or blue, because he can see that the first monks already have their hands up, and he can also see the red dots and reason that each has also seen the red dots.
The monk who answered was sure because he came out first or second and realized that the other monk's reaction meant that he had a red dot and spoke up as soon as it was polite to do so. Poor #3 never had a chance.

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