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

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

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

You have an empty wine bottle with a cork that has been secured at the top in a normal way. There is a metal ring inside the bottle that is suspended by a string.

How can you make the metal ring drop to the bottom if you are not allowed to touch anything - not the bottle, not the cork, not the thread and not the ring?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

John left on a horse on Thursday , was gone for two days, and came back on Thursday after completing his work. How did that happen?

Take one out and scratch my head, I am now black but once was red. What am I?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

What animal walks on four legs in the morning, two legs during the day, and three legs in the evening?

Oedipus, the king of Thebes, figured out the answer to the riddle:

You have two bottles of pills marked with labels A and B. The pills are identical. The doctor has asked you to take one A pill and one B pill daily. You cant take more or less than that.

While taking out the pills one day, you took out one pill from A and by mistake took out two from B. You have no idea which pill is which now.

You cant throw away the expensive pills. What will you do now?