Last week, the local Primary school was visited by the Government School Inspector who was there to check that teachers were performing well in their respective classes. He was very impressed with one particular teacher. The Inspector noticed that each time the class teacher asked a question, every child in the class put up their hands enthusiastically to answer it. More surprisingly, whilst the teacher chose a different child to answer the questions each time, the answers were always correct.
Why would this be?
The children were instructed to ALL raise their hands whenever a question was asked. It did not matter whether they knew the answer or not. If they did not know the answer, however, they would raise their LEFT hand. If they knew the answer, they would raise their RIGHT hand. The class teacher would choose a different child each time, but always the ones who had their RIGHT hand raised.
One morning an airline president is leaving on a business trip and finds he left some paperwork at his office. He runs into his office to get it and the night watchman stops him and says, "Sir, don't get on the plane. I had a dream last night that the plane would crash and everyone would die!"
The man takes his word and cancels his trip. Sure enough, the plane crashes and everyone dies. The next morning the man gives the watchman a $1,000 reward for saving his life and then fires him.
Why did he fire the watchman that saved his life?
Three playing cards in a row. Can you name them with these clues? There is a two to the right of a king. A diamond will be found to the left of a spade. An ace is to the left of a heart. A heart is to the left of a spade. Now, identify all three cards.
Two workmen were repairing a roof. Suddenly, they both fell down the chimney and found themselves in the large fireplace.
One man`s face was smeared with soot and one wasn`t. The one with the clean face washed his and the dirty man did not and went back to work. Why?
When the two men looked at each other, the clean man thought his face was dirty as well. The dirty man, looking at the first's place, thought his was clean.
One company had two factories, in different parts of the country, that were making the same style of shoes. In both factories, workers were stealing shoes. How, without using any security, could that company stop the stealing?
Make one factory make the left shoe, and the other make the right shoe.
A duke was hunting in the forest with his men-at-arms and servants when he came across a tree.
Upon it, archery targets were painted and smack in the middle of each was an arrow.
"Who is this incredibly fine archer?" cried the duke. "I must find him!"
After continuing through the forest for a few miles he came across a small boy carrying a bow and arrow.
Eventually the boy admitted that it was he who shot the arrows plumb in the center of all the targets.
"You didn't just walk up to the targets and hammer the arrows into the middle, did you?" asked the duke worriedly.
"No my lord. I shot them from a hundred paces. I swear it by all that I hold holy."
"That is truly astonishing," said the duke. "I hereby admit you into my service."
The boy thanked him profusely.
"But I must ask one favor in return," the duke continued.
"You must tell me how you came to be such an outstanding shot."
How'd he get to be such a good shot?
The boy shot the arrow, then painted the circle around it.
While mixing sand, gravel, and cement for the foundation of a house, a worker noticed a small bird hopping along the top of the foundation wall. The bird misjudged a hop and fell down one of the holes between the blocks. The bird was down too far for anyone to reach it and the hole was too small for it to fly out of. Someone suggested using two sticks to reach down into the hole and pull the bird out, but this idea was rejected for fear it would injure the fragile bird. What would be the easiest way to get the bird out of the hole without injuring it?
Since they had plenty of sand available, they could pour a little at a time into the hole. The bird would constantly keep shifting its position so that it stood on the rising sand.
Sam is talking to his lawyer in jail. They are very upset because the judge has refused to grant bail. At the end of the conversation Sam is allowed to leave the jail. Why?
Sam is visiting his lawyer, who had been arrested and jailed.
A murdered is condemned to death.
He has to choose between three rooms.
The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years.
Which room is safest for him?
The third room. Lions that haven't eaten in three years are dead.
There are 1 million closed school lockers in a row, labeled 1 through 1,000,000.
You first go through and flip every locker open.
Then you go through and flip every other locker (locker 2, 4, 6, etc...). When you're done, all the even-numbered lockers are closed.
You then go through and flip every third locker (3, 6, 9, etc...). "Flipping" mean you open it if it's closed, and close it if it's open. For example, as you go through this time, you close locker 3 (because it was still open after the previous run through), but you open locker 6, since you had closed it in the previous run through.
Then you go through and flip every fourth locker (4, 8, 12, etc...), then every fifth locker (5, 10, 15, etc...), then every sixth locker (6, 12, 18, etc...) and so on. At the end, you're going through and flipping every 999,998th locker (which is just locker 999,998), then every 999,999th locker (which is just locker 999,999), and finally, every 1,000,000th locker (which is just locker 1,000,000).
At the end of this, is locker 1,000,000 open or closed?
Locker 1,000,000 will be open.
If you think about it, the number of times that each locker is flipped is equal to the number of factors it has. For example, locker 12 has factors 1, 2, 3, 4, 6, and 12, and will thus be flipped 6 times (it will end be flipped when you flip every one, every 2nd, every 3rd, every 4th, every 6th, and every 12th locker). It will end up closed, since flipping an even number of times will return it to its starting position. You can see that if a locker number has an even number of factors, it will end up closed. If it has an odd number of factors, it will end up open.
As it turns out, the only types of numbers that have an odd number of factors are squares. This is because factors come in pairs, and for squares, one of those pairs is the square root, which is duplicated and thus doesn't count twice as a factor. For example, 12's factors are 1 x 12, 2 x 6, and 3 x 4 (6 total factors). On the other hand, 16's factors are 1 x 16, 2 x 8, and 4 x 4 (5 total factors).
So lockers 1, 4, 9, 16, 25, etc... will all be open. Since 1,000,000 is a square number (1000 x 1000), it will be open as well.
