Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

I am a word that begins with the letter “i.” If you add the letter “a” to me, I become a new word with a different meaning, but that sounds exactly the same. What word am I?

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

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?

You see me once in June, twice in November, and not at all in May. What am I?

What do you see in the image below

Who has married many women but was never married?

I am the fastest animal but cannot climb the tree. What am I?

There is something which you can be arrested for attempting but not for successfully completing.

I went to the bookshop and spent one-half of the money that was in my purse.

When I came out, I found that I had as many cents as I had dollars and half as many dollars as I had cents when I went in. Find the money in my purse when I entered the store.