It's not all prime numbers odd. You forget 2 which is prime and even.

Then if p=2 and q=3 then p+q=2+3=5=r and p,q,r are all primes.

Same if p=2 and q=5 then r=7.

Check if there are any more...

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- Jul 28th 2009, 10:52 PM #1

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## Question

Three numbers p, q and r are all prime numbers less than 50 with the property that . How many values of r are possible?

I would think this is 0 because prime numbers have to be odd and odd + odd always equals an even number. But the answer is not 0

- Jul 28th 2009, 11:21 PM #2

- Jul 28th 2009, 11:25 PM #3

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- Jul 28th 2009, 11:28 PM #4

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- Jul 28th 2009, 11:35 PM #5

- Jul 28th 2009, 11:36 PM #6

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- Jul 29th 2009, 12:11 AM #7

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