Question: Please can you tell me something about "powers", which I think are also called "indices". Some examples would also help me.

Answer: Think of these numbers:

2 to the power 4
This means 2 x 2 x 2 x 2 = 16

2 to the power 3
This means 2 x 2 x 2 = 8

2 to the power 2
This means 2 x 2 = 4

2 to the power 1
This means 2 x 1 = 2

Continue this down:

2 to the power 0

This means 1 (Anything to the power 0 is always 1)

2 to the power -1

This means 1/2 or 0.5

2 to the power -2
This means 1/4 or 0.25 (You divide 1 by 2 squared)

2 to the power -3
This means 1/8 or 0.25 (You divide 1 by 2 cubed)

If you look back through this you should see that there is a relationship between positive and negative powers. The negative power is the inverse or reciprocal of the number.