need one more explanation

Question

Very small numbers are often written in exponential form using scientific notation to make them easier to multiply or divide. Explain how to apply the laws of exponents when multiplying and dividing numbers written in scientific notation.

Answer 1

20 = 2 x 10^1

400 = 4 x10^2

400/20 = 20

4 x10^2 divided by 2 x 10^1 = 4/2 x 10^(2-1) = 2 x 10^1 = 2 x 10 = 20

20 x 400 = 8,000

2 x 10^1 x 4 x 10^2 = 8 x 10^(1+2) = 8 x 10^3

when you divide subtract the exponents when you multiply add the exponents

with small numbers where the power of 10 is negative, you do the same. if the powers were 10^-3 and that were divided by 10^-4, then -3 - -4 = -3 + 4 = 1

10^-3/10^-4 = 10^1 = 10

10^-3 times 10^-4 = 10^(-3 + -4) = 10^-7