You can always just do 136/1000 and call it good. The way to look at it is, move the decimal places over as many times necessary to have nothing on the right side, then take that new number. Now, make sure you know how many decimal places you moved it, because you are going to do 1### where the #'s are 0's for how many decimal spots you used. I realize this is convoluted so here's some examples.
.12 as a fraction is 12/100 since I moved the decimal two places to the right so it was 1 and 2 zeros.
.134 as a fraction is 134/1000 since I moved the decimal 3 places to the right, so it was 1 and 3 zeros for 1000.
