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Who is afraid of 7 (or 23) ? (Posted on 2010-11-08) Difficulty: 3 of 5
No matter how we permute the 3 digits 1,2 4 , none of the 6 three- digit numbers (124,142,214,241,412,421) is a multiple of 7.

Clearly, out of 84 possible triplets created by choosing distinct non-zero digits
there must be several like this, i.e. generating a 6-pack of three-digit numbers,
non divisible by 7.

1. List those triplets.
2. Similar question re:4 digits and divisibility by 23.

No Solution Yet Submitted by Ady TZIDON    
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Comments: ( Back to comment list | You must be logged in to post comments.)
Question re: computer solution | Comment 3 of 5 |
(In reply to computer solution by Charlie)

Who needs 23 now?

It never crossed my mind to check 4 digits  and the divisibility by SEVEN.

 

How about 5 digits?7


  Posted by Ady TZIDON on 2010-11-08 16:46:37
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