Find the next number in the series below

21 32 54 87 131 ?

I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

O_er_t_o_

Complete the missing letters of the given word.

What can go up a chimney down, but can’t go down a chimney up?

You need to remove two matchsticks to make the below equation true. Can you do it ?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

A spy was in Canada trying to steal insider information on how to set up new Maple Syrup factories in their country. He was introduced to the operations manager of the biggest factory in Canada. However, the manager was suspicious and decided to test him with a question before he trusted him. So he asked, “What would you be sure to find in the middle of Toronto?” The spy thought fast and came up with an answer for the manager. What was his answer?

I am written with two letters.
I said with the one.
I usually am seen with the two.

Who am I?

What has many keys but can’t open a single lock?