Prove that one can find infinite number of distinct pairs of integers such that every digit of each number is no less than 7 and the product of two numbers in each pair is also a number with all its digits being no less than 7. (6)
Source:
Tags: number theory, combinatorics
Prove that one can find infinite number of distinct pairs of integers such that every digit of each number is no less than 7 and the product of two numbers in each pair is also a number with all its digits being no less than 7. (6)