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

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

Can it be possible to build a house that has all its four walls facing towards the South?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

A donkey is behind another donkey
I'm behind that second donkey
But there is a whole nation behind me

It is a murder you can describe in a word.

Can you identify the famous TV character from the rebus below?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?