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?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

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.

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

There are hundred red gems and hundred blue gems. The blue gems are priceless while the red gems equal wastage. You have two sacks one labeled Heads and the other Tails. You have to distribute the gems as you want in the two sacks. Then a coin will be flipped and you will be asked to pick up a gem randomly from the corresponding sacks.

How will you distribute the gems between the sacks so that the odds of picking a Blue gem are maximum?

What do you think with the below Picture ?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

Your mother’s brother’s only brother-in-law is asleep on your couch. Who is asleep on your couch?