Can you count the number of triangles in the given picture?

The more of this there is, the less you see. What is it?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

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

O T T F F S S ?

What begins with T, ends with T, and has T in it?

In the city of Brain Teasers, 5% of people do not list their phone numbers. Now if we select random 100 people from the phone directory, then how many people selected will have unlisted phone numbers?

What number when divided in half becomes zero?

How many triangles are there on the puzzle below?

Find the Odd One Out?
84129
32418
47632
36119
67626
72927