Problem Solving

I have the answers in the back, but need help setting this up:

On a scale that measures the intensity of a certain phenomenon, a reading of n+1 corresponds to an intensity that is 10 times the intensity corresponding to a reading of n. On that scale, the intensity corresponding to a reading of 8 is how many times as great as the intensity corresponding to a reading of 3?

Not sure the answer is what it is...

To solve by induction, you can directly do
Intensity at level n = 10^n * intensity-at-level-1

Alternatively,

Intensity at 4 = 10 * intensity at 3
Intensity at 5 = 10^2 * intensity at 3
...
Intensity at 8 = 10^5 * intensity at 3

Thanks for the explanation.

How would I identify induction problems going forward? I wasn't really sure how to set this one up when I read the problem.