Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

How can you tell a raw egg from a hard-boiled egg?

I look flat, but I am deep. Hidden realms I shelter. Lives I take, but the food I offer. At times I am beautiful. I can be calm, angry, and turbulent. I have no heart but offer pleasure as well as death. No man can own me, yet I encompass what all men must have. What am I?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?

Why do you find that most of the buildings are deprived of the 13th floor?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).

It is always ahead of me yet I can never see it. What is it?