If 21x = 79x, what is the value of x?

On my way to St. Ives I saw a man with 7 wives. Each wife had 7 sacks. Each sack had 7 cats. Each cat had 7 kittens. Kittens, cats, sacks, wives. How many were going to St. Ives?

How is the moon similar to a dollar?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

There are two guys standing face to face in a room. On a wall, there is a clock. One of those is a prophet. He tells the other guy that he will be stabbed in the back in five minutes.

Shocked to hear that, the other guy stares at the clock. Just after the five minutes, he is stabbed on the back. Can you tell what happened?

No matter how little or how much you use me, you change me every month. What am I?

How can you make number one disappear by adding something to it?

Find the next number in the series.
1 10 24 43 67 ?

If a shopkeeper can only place the weights on one side of the common balance. For example, if he has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names of the weights you will need to measure all weights from 1 to 1000? This is a fairly simple problem and very easy to prove also.