Can you make four (4) nines (9) equal 100?

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

What does this simple rebus mean?

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.

I’m tall when I’m young, and I’m short when I’m old. What am I?

How can a man go eight days without sleep?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?