If pq is a rational number with terminating decimal expansion where p and q are coprimes, then q can be represented as:
(Here, n and m are non-negative integers.)
2n5m
If pq is a rational number with terminating decimal expansion where p and q are coprimes, then the prime factorisation of q will be in the form of 2n5m.
Example:
Consider rational number 18.
Here, denominator 8=23×50
Therefore, the rational number 18 will have terminating decimal expansion.
18=0.125 which is terminating.
Hence verified.