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?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

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

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

How many triangles are there on the puzzle below?

What is the end of everything?

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

Using Only Five 5's and any mathematical operator make sum as 37

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?