Look at several examples of rational numbers in the p/q(q is not equal to 0)

We observe that when q is 2, 4, 5, 8, 10… then the decimal expansion is terminating.

For example: 1/2 = 0.5͞, denominator q = 21 7/8 = 0.͞8͞7͞5, denominator q = 23 4/5 = 0.8͞, denominator q = 51

It can be observed that the terminating decimal can be obtained in a condition where prime factorization of the denominator of the given fractions has the power of 2 only or 5 only or both.