How Are They Similar?

Number Theory Level 4

\[\large 100^m-9^n\\ \large 64^j-7^k\]

Let \(m, n, j\) and \(k\) be positive integers. If \(A\) and \(B\) are the smallest positive integers that can be written in the form of the first and the second expressions above respectively, find \(A\times B\).