Find the area of the shaded region in the figure below, if the radius of the outer circle is 10 and the radius of the inner circle is 8. Keep your answer is terms of pi.

I assume that the figure your figure is like this:

the mistake in the pattern is that :

b. the decimal point was moved one too many place values each time

the correct pattern could be made by :

b. moving the decimal point to the right the same numbers of place values as the exponents