Denote by R(N) the integer obtained by reversing the digits of a positive integer N.
Determine the largest integer that is certain to
divide N^{4}  (R(N))^{4}, with N > R(N), regardless of the choice of N.
(In reply to
re: possible computer solution by Ady TZIDON)
You are absolutely correct.
With
For n = 10 To 10000
rn = reverse(n)
If n > rn Then
If flag = 0 Then
sofar = n * n * n * n  rn * rn * rn * rn
flag = 1
Else
sofar = gcd(sofar, n * n * n * n  rn * rn * rn * rn)
End If
Text1.Text = Text1.Text & Str(n) & Str(rn) & Str(sofar) & crlf
DoEvents
End If
Next
the GCD comes out as 99.

Posted by Charlie
on 20140722 13:43:14 