Can you place three balls such that the equation shown in the picture holds true?

You can hear me, but you can't touch or see me.

What am I?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

If,

20 % 5 = 24

21 % 7 = 33

42 % 6 = 67

Then;

66 % 6 = ?

Count the number of balls in picture below:

Can you solve the maths in the below-given picture equation?

What is the next number in this series?

4,12,84,3612....

81 x 9 = 801. What must you do to make the this equation true?

In the picture, you can see a chess board. On the top left position, the K marks a knight. Now, can you move the knight in a manner that after 63 moves, the knight has been placed at all the squares exactly once excluding the starting square?

If two's company, and three's a crowd, then whats four and five ?