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Prime it remains (Posted on 2013-01-15) Difficulty: 3 of 5
What is the smallest prime remaining prime when added to its reverse?

Analytical solution preferred.

No Solution Yet Submitted by Ady TZIDON    
Rating: 4.0000 (2 votes)

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Solution computer solution | Comment 1 of 4

   10   for I=1 to 100
   20   P=prm(I)
   30   S=cutspc(str(P))
   40   R=""
   50   for J=1 to len(S)
   60      R=mid(S,J,1)+R
   70   next
   80   Rev=val(R)
   90   P2=P+Rev
  100   if prmdiv(P2)=P2 then print P,Rev,P2
  110   next
 
finds

prime    rev    new prime 
 229     922     1151
 239     932     1171
 241     142     383
 257     752     1009
 269     962     1231
 271     172     443
 277     772     1049
 281     182     463
 439     934     1373
 443     344     787
 463     364     827
 467     764     1231
 479     974     1453
 499     994     1493

The smallest is 229.

Only primes up to the 100th prime were checked.


  Posted by Charlie on 2013-01-15 17:59:45
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