Sender: "Marlene Moore"

Hi...Im in 9th grade and am having a hard time figuring out symmetric primes. Heres the problem:

Find two pairs of symmetric primes of 20. Symmetric primes of 15?

How do I go about solving this?

I am not sure what you mean by symmetric primes. By symmertic primes of 20 do you mean primes two primes with 20 midway between them? If so I would try an orderly search, starting at 20.

• 21 in not a prime
• 22 is not a prime
• 23 is a prime.
  • 23 = 20 + 3
  • 20 - 3 = 17 and 17 is also a prime
  • Thus 23 and 17 is one pair of symmetric primes of 20

• 24 is not a prime
• 25 is not a prime
• .
• .