100% , 3/25 , 1 x 10^1 , 1/10 , 0.111 greatest to least

First we convert all these numbers to fractions with their Least Common Denominator. In this case it is 1000.

A = 100% = 1000/1000

B = 3/25 = 120/1000

C = 1*10^1 = 10 = 10000/1000

D = 1/10 = 100/1000

E = .111 = 111/1000 

Now we order them from greatest to smallest by how large the number on the top side of the fraction is. For example, E, 111/1000, is greater than D, 100/1000, because 111 is larger than 100.

Arranging them from greatest to smallest gives us C, A, B, E, D.