What word is pronounced the same if you take away four of its five letters?

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

On a bus, there is a 26-year-old pregnant lady.
A 30-year-old policeman.
A 52-year-old random woman.
And the 65-year-old driver.

Who is the youngest?

How many sides does a circle have?

You know three triplets: Frank John and Wayne (need to return your money). Frank always tells the truth while John and Wayne always lie. You meet one of them on the road and can ask him a three-word question.
Which question, will you ask?

Solve the rebus riddle in the picture below.

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?

If two fifty-foot ropes are suspended from a forty-foot ceiling that is twenty feet apart, how much rope will you be able to steal if you have a knife?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?