Primes whose reversed number is also prime: Difference between revisions

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(Created page with "{{Draft task}} ;Task:Find and show here in base ten primes whose reversed number is also prime and not equals, where '''n < 1,000''' <br><br> =={{header|Ring}}== <lang ring...")
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Revision as of 02:48, 30 July 2021

Primes whose reversed number is also prime is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
Task
Find and show here in base ten primes whose reversed number is also prime and not equals, where n < 1,000



Ring

<lang ring> load "stdlib.ring" see "working..." + nl see "Primes whose reversed number is also prime:" + nl row = 0

for n = 1 to 1000

   strn = string(n)
   strn = rever(strn)
   strn = number(strn)
   if isprime(n) and isprime(strn) and n != strn
      see "(" + n + "," + strn + ")" + " "
      row++
      if row%5 = 0
         see nl
      ok
   ok    

next

see nl + "Found " + row + " prime numbers" + nl see "done..." + nl

func rever(str)

    strb = ""
    for n = len(str) to 1 step -1
        strb += str[n]
    next
    return strb

</lang>

Output:
working...
Primes whose reversed number is also prime:
(13,31) (17,71) (31,13) (37,73) (71,17) 
(73,37) (79,97) (97,79) (107,701) (113,311) 
(149,941) (157,751) (167,761) (179,971) (199,991) 
(311,113) (337,733) (347,743) (359,953) (389,983) 
(701,107) (709,907) (733,337) (739,937) (743,347) 
(751,157) (761,167) (769,967) (907,709) (937,739) 
(941,149) (953,359) (967,769) (971,179) (983,389) 
(991,199) 
Found 36 prime numbers
done...