You divide the numerator by the denomenator to get a decimal.Sometimes the number keeps on going for a long time.
You could also find how many times the denomenator goes into 100. You multiply that number by the numerator.
You divide the numerator by the denominator. You can use a calculator, or do it by hand, just carry out the decimal points.
It's long sorry:
... get your calculator and type in "5 / 8 ="
The answer should be 0.625