9/250. The 3 in 0.036 is in the hundredths place. This works the same as if it were just 0.03. if it were 0.03, you would divide 3 by 100, (3/100), so now you will divide 3.6 by 100. this will get you 3.6/100. you want to make that a whole number in the numerator so multiply the numerator and denominator by 10. then you have 36/1000 which simplifies to 9/250 (divide both by four).
If that is too complicated, think of it like this:
36 is a whole number. we like whole numbers because they are easy. how many decimal places would you have to move to get 0.036? the answer is three. so that can be written as 36 over a one with three zeros. (36/1000)