Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

Which number should replace the question mark?

I travel all around the world but always stay in the corner. What am I?

Can you find the next number in the below sequence
3 , 7 , 10 , 11 , 12 , 17 ?

John is pretty weird. He likes toffees but hates chocolates. He loves books but never reads. He likes to build his troops in an online game but does not proceed with the war. He likes to go swimming but is afraid of water.

Seeking this behaviour, can you tell whether he likes balloons and parties?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

Find the value of "a" by solving the maths equation in the picture below:

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.