Can you convert the number zero(0) into a positive number using just one mathematical operator ?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

There are five men, let's say Tarun Harish Lavesh, Manoj, and Manish. All of them have a dot mark on their forehead. They can't see the dots on their forehead but can see the ones on others. The owner of WHITE Dot is an honest person and will never lie, while the owner of BLACK Dot always tells the lie.

This is the statement from Tarun Harish Lavesh and Manish:
Tarun: 'I see 3 whites and 1 black'
Harish: 'I see 4 black'
Lavesh: 'I see 3 black and 1 white'
Manish: 'I see 4 white'

What colour is the dot on each of Tarun Harish Lavesh, Manoj, and Manish's forehead?

Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

You can see it everyday, But cannot touch it at will. What is it?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

Which part of London exists in France as well ?

What is the difference between a jeweller and a jailer?