There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

Three people enter a room and have a green or blue hat placed on their heads. They cannot see their own hat but can see the other hats.
The colour of each hat is purely random. They could all be green, blue, or any combination of green and blue.
They need to guess their own hat colour by writing it on a piece of paper, or they can write 'pass'.
They cannot communicate with each other in any way once the game starts. But they can have a strategy meeting before the game.
If at least one of them guesses correctly they win $10,000 each, but if anyone guesses incorrectly they all get nothing.
What is the best strategy?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

What does the rebus below mean?

TEN BADTION

Two friends were betting. One said to the other, "The coin will be flipped twenty times and each time the coin lands on the head, I will give you $2 and each time it lands on the tale, you will give me $3." After flipping the coin twenty times not a single penny was exchanged among them.

How many times did the coin land on heads?

John is found dead in his office at his desk. The police have narrowed the suspects down to three people: Mrs. Jacob, John’s wife Hena and his business partner Jason . All three visited John on the day of his murder, but all three provide the police with stories of explanation as to the reason for their visit.
Police found John with his wrist watch still on his right arm, a torn up picture of his wife laying on the floor beside the trash can, and an ink pen in his right hand. On the desk, the police found a name plate, a telephone that was off the hook, and a personal calendar turned to the July 5th page with 7B91011 written on it. After examining this evidence, the police knew their suspect. Who was it ?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?