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

I have two coins.
* One of the coins is a faulty coin having a tail on both sides of it.
* The other coin is a perfect coin (heads on side and tail on other).

I blindfold myself and pick a coin and put the coin on the table. The face of the coin towards the sky is the tail.

What is the probability that another side is also tail?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

A chicken farmer has figured out that a hen and a half can lay an egg and a half in a day and a half. How many hens does the farmer need to produce one dozen eggs in six days?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

John can fit six large chocolate boxes or nine small chocolate boxes into a carton. How many cartons will he require to put sixty-six chocolate boxes into?

Can you find out the remainder when 3^300 is divided by 5?

Divide 110 into two parts so that one will be 150 per cent of the other. What are the 2 numbers?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?