1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

Find out the missing number in the picture attached:

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

81 x 9 = 801. What must you do to make the this equation true?

Something Extraordinary happened on May 6th 19778 at 12:34am what was that?