Can you place six X (crosses) in below board without making three in a row in any way ?

Do You See It?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

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

Replace the (?) with the correct mathematical signs to make the expression equal to 59.

18 ? 12 ? 4 ? 5 = 59

How is a fly different from a mosquito?

Different lights make me strange by changing me into different sizes. What am I?

If two's company, and three's a crowd, then whats four and five ?

I am white when I am dirty, and black when I am clean. What am I?

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.