Question

Could someone help me? the video doenst explain it

Answer 1

Personally, I would recommend reading this as a fraction, and splitting up mantissa from the power of 10. (Mantissa refers to the number 1.23 in
`1.23*10^n`.)

`\left(3.6 * 10^(-5)\right) / \left(9 * 10^(-7)\right) = (3.6 * 10^(-5))/(9 * 10^(-7)) = \frac{3.6}9 * (10^(-5))/(10^(-7))`

Now just reduce each fraction:

`\frac{3.6}9 = (36)/(90) = \frac25 = 0.4`

`(10^(-5))/(10^(-7)) = 10^(-5-(-7)) = 10^(-5+7) = 10^2`

So

`\left(3.6 * 10^(-5)\right) / \left(9 * 10^(-7)\right) = 0.4 * 10^2 = \boxed{4 * 10^1}`

since
`0.4*10^2 = 0.4 * 100 = 40 = 4 * 10`.