Place the numbers in descending order

2.3x10^-10; 3.2 x 10^-10; 2.3 x 10^-12; 2.3 x 10^-8

3.2 x 10^-10, 2.3 x 10^-10, 2.3 x 10^-8, 2.3 x 10^-12