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A logical search (Posted on 2018-09-24) Difficulty: 2 of 5
Find the smallest prime that remains prime
when added to its reversal

P&P solution preferred

See The Solution Submitted by Ady TZIDON    
Rating: 1.5000 (2 votes)

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Solution answer | Comment 3 of 10 |
As two odd numbers added together will be even and the only even prime is 2, the smallest prime that remains prime must be in the form 2XN where X represents zero or more digits and N is an odd digit other than 3 or 5 (as, but for the number 5, no prime number can end in 5; and 3+2 = 5).

Iterating through the possible primes from lowest upward, the fourth prime number that passes the aforementioned restrictions is 229. 229 + 922 = 1151 is prime.


Edited on September 24, 2018, 4:26 pm
  Posted by Dej Mar on 2018-09-24 16:10:19

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