List the numerator’s factors, which are the integers that the numerator can be divided by without leaving a remainder. For an example, let the fraction be 6/60. For the numerator 6, the factors are 1, 2, 3 and 6.
List the denominator’s factors. For the denominator 60, the factors are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 and 60.
Find the greatest common factor of the numerator and denominator, which is the largest number included in both factor lists. For this example, 6 is the largest factor found in both lists.
Divide both numerator and denominator by their greatest common factor to reduce the fraction to its simplest terms. In this example, dividing 6 by 6 results in 1, and dividing 60 by 6 results in 10. The fraction 6/60 becomes 1/10.
List the reduced denominator’s factors. Circle the prime numbers in the list that are higher than 1. Prime numbers are positive integers that are only divisible by 1 and the number itself. If you have circled a 2 or a 5 or both, and no other prime numbers, then the fraction will convert into a terminating decimal. Concluding this example, the factors of 10 are 1, 2, 5 and 10, with the only prime numbers higher than 1 being 2 and 5. Thus, the fraction 6/60 converts into a terminating decimal.