When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is 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?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Once while in his court, King Akbar asked Birbal to write something on a wall that makes one sad when read in good times and makes one happy when read in sad times.

He took only a few moment and wrote something that fit the requirements. What did he write?

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

There's a day, that comes around once a year.
To celebrate the man, you hold dear.
He gave you life, love and will pick you up if you fall.
When it comes to guys like him, He's the best of all.
Who is he?

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?

Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol?

19834 -----: 187
15921 -----: 153
17561 -----: 139
13734 -----: ???

Buy me, smell me or deliver me, I do not change.

Who am I?