Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Yesterday I fell from 30 feet high ladder but I don't get hurt. Why?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

Why are all black people so quick ?

A prisoner is told: "If you tell a lie, we will hang you and if you tell the truth, we will shoot you." What did the prisoner say to save himself?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

John is found dead in his office at his desk. The police have narrowed the suspects down to three people: Mrs. Jacob, John’s wife Hena and his business partner Jason . All three visited John on the day of his murder, but all three provide the police with stories of explanation as to the reason for their visit.
Police found John with his wrist watch still on his right arm, a torn up picture of his wife laying on the floor beside the trash can, and an ink pen in his right hand. On the desk, the police found a name plate, a telephone that was off the hook, and a personal calendar turned to the July 5th page with 7B91011 written on it. After examining this evidence, the police knew their suspect. Who was it ?

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

When is the top of a mountain similar to a savings account?