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

When can we add 2 to 11 and get 1 as the correct answer?

There is a jar in which there are two types of candies.
20 blueberries and 16 strawberries. You perform the following steps:
1) You take out two candies.
2) If the two candies are of the same flavour, you add a blueberry one otherwise, you add the strawberry one.

You repeat these two steps till there is just one candy remaining in the jar. Which flavoured candy will be left?

Intelligence Agency need to break the vault but the problem is that they are not able to break the vault.

On the vault, a text is written as:

31 11 33 33 43 45
21 25
31 24 11 31 51 41

To Break the code Intelligence Agency brings a mathematician named Joseph.
Minutes later he deciphers the code.

Whats the code?

I shave every day, but my beard stays the same. What am I?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

If,
9 * 8 * 7 = 65
8 * 7 * 6 = 50
7 * 6 * 5 = 37

Find
6 * 5 * 4 = ?

Find the next number in the series.
1 10 24 43 67 ?

What is the centre of gravity?