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

O T T F F S S ?

Solve the mathematical equation in the picture below.

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

What is full of holes but still holds water?

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Chocolate costs 6 rupees and a Toy costs 5 rupees. If you have 32 rupees in total, how many chocolates and how many Toys can be purchased with that amount?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different. How do you measure 45 minutes?