What is the largest existing n-digit pandigital (i.e.using all digits from 1 to n) prime number ?

  100   for N=2 to 9
  120    V$=left("123456789",N):H$=V$
  200    Max=0
  215    repeat
  220     gosub *Permute(&V$)
  230     P=val(V$)
  240     if prmdiv(P)=P then if P>Max then Max=P
  250    until V$=H$
  260    if Max>0 then print Max
  300   next N
  800   end

finds

 4231
 7652413
 
 So only n=4 and n=7 work and these are the only two solutions.
 
 Of course if "largest" means the "largest for all values of n", rather than "for each value of n", then of course 7,652,413 is it.

Posted by Charlie on 2012-09-01 13:35:26