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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- July 28th 2009, 11:52 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

- July 29th 2009, 12:21 AM #2

- July 29th 2009, 12:25 AM #3

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- July 29th 2009, 12:28 AM #4

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- July 29th 2009, 12:35 AM #5

- July 29th 2009, 12:36 AM #6

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- July 29th 2009, 01:11 AM #7

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