It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

If,
9 * 8 * 7 = 65
8 * 7 * 6 = 50
7 * 6 * 5 = 37

Find
6 * 5 * 4 = ?

I can write cow in 13 letters.

Can You?

How could a baby fall out of a twenty-story building onto the ground and live?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.