What seven-letter word has hundreds of letters in it?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

Replace the question mark with the correct number in below Picture:

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

This was asked in an interview with Coa-Cola.

The interviewer has given me 100 marbles(50 white and 50 black) and two empty boxes.
He then told me that he will leave the room and i need to place all the marbles in two boxes.

And When he come back, he will draw a marble from any of the two box and if the marble is white I will be hired.

Also
* No box can be empty.
* All 100 marbles must be placed in one of the two boxes.

So what should I have done?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

Count the number of balls in picture below:

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

Two fathers and two sons went fishing one day. They were there the whole day and only caught 3 fish. One father said, that is enough for all of us, we will have one each. How can this be possible?