The public library has an approximate length of 1 x 10^5 millimeters and width of 8 x 10^4 millimeters. what is the area, in square milliters, of the public library?
a. 8 x 10^9 square millimeters
b. 9 x 10^9 square millimeters
c. 8 x 10^20 square millimeters
d. 9 x 10^20 square millimeters