Find the next number in the sequence

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

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

In a secret society, a buried chamber can be accessed only via a secret password. The password is seven characters long and comprises of just letters and numbers.

You find a code that can help you in cracking the password. The code says "You force heaven to be empty".

Can you deduce the password from that?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

As we know that white starts the game of chess. Can you find the scenario shown in the picture below is possible when all the white pieces are at the original place while the black pawn is not as in the below picture?

Find the next number in the following series:
6, 14, 26, 98, __?

You are in a room with no metal objects except for two iron rods. Only one of them is a magnet.
How can you identify which one is a magnet?

A woman lives in a skyscraper thirty-six floors high and is served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

Can you count the number of triangles in the given picture?

Using Only Five 5's and any mathematical operator make sum as 37