logorithms

$6 = \log\left(\dfrac{I_1}{I_s}\right) \\ 8=\log\left(\dfrac{I_2}{I_s}\right) \\ 10^6=\dfrac{I_1}{I_s}\\ 10^8=\dfrac{I_2}{I_s} \\ \dfrac{I_2}{I_1} = \dfrac{10^8}{10^6} = 10^2 = 100$

M  =  log   ( I  / S)

In Exponential form, we have

10^M  = (I /S)

So...we have this situation

10^8  = (I₈/S)    ⇒  S * 10^8   =  I₈        (1)  

and

10^6  = (I₆/S)  ⇒   S * 10^6  =  I₆       (2)

So  take the ratio of  (1) / (2)    and we have

I₈ / I₆    =    S* 10^8  / S* 10^6

I₈ / I₆   =  10^8 / 10^6

I₈ / I₆  =   10^(8 - 6)

I₈ / I₆   =  10^2    =   100 times stronger