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

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

If a wheel has 54 spokes, how many spaces are there between the spokes?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

Our product and our sum always give the same answer. Who are we?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

Which country gets ill every time?

How many words can a pen with half refill write?

In the Wild West, you are challenged into a death match by two bounty hunters nicknamed Golden Revolver (GR) and Killer Boots (KB). You accept the challenge. None of you want to waste any of the bullet and so a certain rules are laid down:

1) All of you will shoot in a given order till the last man standing.
2) Each of you shoots only once upon his turn.
3) If any one of you is injured, the other two will finish him off with an iron rod.
4) The worst shooter of all (which is you) shoots first and the best one shoots at the last.

Now, how will you plan things if you know that you hit every third shot of yours, KB hits every second shot and GR hits every shot ?

Move four matchsticks to the below square to form three squares?