How to divide 42 over 45.5 without calculator and get 12 over 13

We divide 42 over 45.5 and get an answer of 12 over 13 by factoring both the numerator and the denominator in which we expect to get the rest of the factors to be whole numbers. The common factor for both the numerator and denominator is 3.5. 42 divided by 3.5 is 12 and 45.5 divided by 3.5 is 13.