Hi Taylor,
The Richter scale is logarithmic and the scale is the exponent of base ten.
so the magnitude of the 7.9 would be 107.9
and the magnitude of the 4.81 would be 104.81
if we divide these two values
107.9 / 104.81
we get 103.09
and this number is greater than 1000
so the magnitude of the 7.9 versus the 4.81 is over 1000 times greater.
Hope this helps