What is the next number in this series?

4,12,84,3612....

A time long back, there lived a king who ruled the great kingdom of Trojan House. As a part of the renovation of the kingdom to meet future security needs, he asked his chief architect to lay down a new play in a manner that all of his 10 castles are connected through five straight walls and each wall must connect four castles together. He also asked the architect that at least one of his castles should be protected with walls. The architect could not come up with any solution that served all of King's choices, but he suggested the best plan that you can see in the picture below. Can you find a better solution to serve the king's demand?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

How can you take 2 from 5 and leave 4?

What word does this rebus represent?

meta meta
meta meta

Using eight eights and addition only, can you make 1000?

The current time can be represented by below textual rebus.

0
=========
B.Sc
LLB

Can you tell us the current time?