Question

write down what will be the condition any irrational number after decimal expansion​

Answer 1

But what is an irrational number?

Answer 2

Let x = p/q be a rational number such that the prime factorization of q is of the form 2m5n where n m are non-negative integers. Then x has a decimal expansion which terminates. Example:Since the denominator is of the form 2m x 5n the rational number has a terminating decimal expansion.