Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

Prove that twice of ten is the same as twice of eleven.

I make two people out of one. What am I?

Which is heavier: a ton of bricks or a ton of feathers?

From a pack of 52 cards, I placed 4 cards on the table.

I will give you 4 clues about the cards:

Clue 1: Card on left cannot be greater than the card on the right.
Clue 2: Difference between the 1st card and 3rd card is 8.
Clue 3: There is no card of an ace.
Clue 4: There are no face cards (queen, king, jacks).
Clue 5: Difference between the 2nd card and 4th card is 7.

Identify four cards?

A word I know has six letters it contains, remove one letter and 12 remain. What is it?

What does man love more than life, hate more than death or mortal strife; That which contented men desire; the poor have, the rich require; the miser spends, the spendthrift saves, and all men carry to their graves?

The following question it puts forth you:

25 - 55 + (85 + 65) = ?

Then, you are told that even though you might think it's wrong, the correct answer is actually 5!

Whats your reaction to it? How can this be true?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211