If 21x = 79x, what is the value of x?

There are a hundred statements.

First person says: At least one of the statements is false.

Second person says: At least two of the statements is false.

Third person says: At least three of the statements are false.

Fourth person says: At least four of the statements are false.

..

..

..

Hundredth person says: At least a hundred of the statements are false.

Analysing it, how many statements do you think are false and how many are true?

On my way to St. Ives I saw a man with 7 wives. Each wife had 7 sacks. Each sack had 7 cats. Each cat had 7 kittens. Kittens, cats, sacks, wives. How many were going to St. Ives?

There are nine dots in the picture that has been attached with this question. Can you join all the dots by drawing four straight lines without picking up your pen?

Name a key which is hardest to turn.

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

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

What does man love more than life, and hate more than death or mortal strife; that which satisfied men want; the poor have, and the rich require; the miser spends, the spendthrift saves, and all men carry to their graves?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?