The first term of this sequence is -20, and the common ratio is 11. Thus, the formula for the nth term is
a(n) = a(1)*(11)^(n-1), or (-20)*(11)^(n-1).
Thus, the 12th term is
a(12) = (-20)*(11)^(12-1) = -20(11)^11 = -20(2.85 times 10 to the 11th power.
or ... -5.71 times 10 to the 12th power.
