if you use fractions, the answer you get will always be an exact answer in the form of a fraction. resorting to decimals means that you may run into rounding errors and therefore get only an approximate answer. e.g. the fraction 1/3 cannot be exactly represented by a decimal.fractions can be easier to represent the number rather then using decimals which involve writing out many numbers it does not affect the accuracy of the answer UNLESS you are rounding up and down the numbers
