Prove there are no integer solutions for the equation \(4^k - 4^l = 10^n\).
Solve the equation \(x + \frac{1}{(y + 1/z)}= 10/7\) in natural numbers.
Let \(s\) and \(t\) be two positive integers. Can we have \(s^2=t^2+2\)?
Are there any two-digit numbers which are the product of their digits?