How can you make number one disappear by adding something to it?

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

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

If eleven plus two equals one, what does nine plus five equal?

I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

While going to your grandmother's house, you counted Twenty houses on the right side. While returning back to your home, you counted Twenty houses on the left side.

How many houses are there between your home and your grandmother's home?

John can fit six large chocolate boxes or nine small chocolate boxes into a carton. How many cartons will he require to put sixty-six chocolate boxes into?

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

What does the below rebus riddle means?