How can you make number one disappear by adding something to 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

What has to be broken before you can use it?

A clock loses 10 minutes each hour. If the clock is set correctly at noon, what time is it when it reads 3 PM?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

I am white when I am dirty, and black when I am clean. What am I?

Can you replace the question mark with the correct number?

What word is identified by the below rebus?

Your Your Your Your Your
Your Your Your Your Your

Why Aeroplane windows are round?

The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.

What can a student say to prevent his being expelled from school?