Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

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?

Find three whole, positive numbers that have the same answer when multiplied together as when added together.

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

Can you find a five letter word that is left with only two letters if one is removed?

How can you drop a raw egg from a height onto a concrete floor without cracking it?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

After teaching his class all about Roman numerals (X = 10, IX=9 and so on) the teacher asked his class to draw a single continuous line and turn IX into 6. The teacher's only stipulation was that the pen could not be lifted from the paper until the line was complete.

What number comes next in this sequence:
7 8 5 5 3 4 4 _