If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognises the three as friends and asks the waiter to return $5 to the men.

The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself.

Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14. Where has the other $1 gone from the original $15?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

Paul's height is six feet, he's an assistant at a butcher's shop and wears size 9 shoes. What does he weigh?

How many times do a clock's hands overlap in a day ?

What is full of holes but still holds water?

You’ll find me on Mercury, Earth, Mars, Jupiter, Saturn, and Uranus. But never Neptune, or Venus. What am I?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?