MathGroup Archive 2005

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challenge problem

  • To: mathgroup at
  • Subject: [mg61219] challenge problem
  • From: Murray Eisenberg <murray at>
  • Date: Thu, 13 Oct 2005 01:39:29 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • Reply-to: murray at
  • Sender: owner-wri-mathgroup at

At, there are a number 
of interestng programming problems posed.  One, the "Lucky Sevens", is 
to write a program that will find the sum of all those integers between 
1 and 10^11 that are divisible by 7 AND whose reversed-digit forms are 
also divisible by 7.

I should think that an elegant and possibly efficient solution in 
Mathematica would be to use the form func /@ Range[10^11].  But since 
Mathematica 5.2 on my my 32-bit Windows machine won't let me form 
Range[10^11], a 64-bit architecture would seem to be required.

Murray Eisenberg                     murray at
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

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