Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

What runs around the whole yard without moving?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

James bond was pushed out of an aeroplane without any parachute.
He survived, How come?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

I have an eye but still cannot see.

Who am I?

Can you name an animal whose killing cannot be performed without spilling your own blood?