The more of this there is, the less you see. What is it?

Assume the given figure to be a delicious doughnut. Yes, now you can concentrate more on the puzzle. So you have this delicious doughnut in your refrigerator when your friends come knocking at the door. There are eight of them. Now you have to make three cuts in this doughnut so that each one of you nine people can enjoy a piece of it. Neither you nor your friends would mind the size of their piece as long as they are getting it. How will you do it?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

Replace the question mark with the correct number.

2 + 2= 4
3 + 3= 18
4 + 4= 48
5 + 5= ?

What runs around the whole yard without moving?

What can you serve, but never eat?

What is the next shape from answers A, B, C, and D figure?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain