Can you find the key in the picture below?

What is the next number in this series?

4,12,84,3612....

There is a box in which distinct numbered balls have been kept. You have to pick two balls randomly from the lot.

If someone is offering you a 2 to 1 odds that the numbers will be relatively prime, for example
If the balls you picked had the numbers 6 and 13, you lose $1.
If the balls you picked had the numbers 5 and 25, you win $2.

Will you accept that bet?

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

The ages of a father and son add up to 66.
The father's age is the son's age reversed.
How old could they be?
(3 possible solutions).

It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?

Yesterday I fell from 30 feet high ladder but I don't get hurt. Why?

What has 13 hearts but no other organs?

What is the coolest letter in the alphabet?

What is the value of 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 of 1000?