If you say my name, I will no longer exist. What am I?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

In front of you, there are 9 coins. They all look absolutely identical, but one of the coins is fake. However, you know that the fake coin is lighter than the rest, and in front of you is a balance scale. What is the least number of weightings you can use to find the counterfeit coin?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

Can you count the number of lines in the below picture?

What does does this rebus picture means ?

I am Huge on Sunday and Saturday.
I am small from Tuesday to Thursday.
I do not exist on Monday and Friday.
Who am I?

What is always in front of you but can’t be seen?

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?