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

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

Find the next number in the sequence

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

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

Why is it very easy to weigh a fish?

John was writing his first book. After saving the document, he locked his laptop with a password and mentioned some phrases for the hint box.

A friend of his tried opening his laptop but found out that it was password protected. Following is the hint that appeared.
1 mobile 3 books 2 roars 1 night 4 balls 2 lighters 1 ghost 1 hat 3 watches.

Can you help him in cracking the password?

Find out a multi-digit number that if multiplied by the number 9 or any of its multiplications products (i.e. 18, 27, 36, 45,..) will result in the multiplication factor repeated (n) number of times.

Solve the puzzle by telling what does below picture means.

Why Aeroplane windows are round?