Thursday, December 17, 2009

What are 2 prime numbers that add up to 488?

I know i made a mistake last question. My apologies, but thanks for the answers!What are 2 prime numbers that add up to 488?
457 + 31 = 488What are 2 prime numbers that add up to 488?
Create a list of all primes between 1 and 488 (answer: there are 94 primes between 1 and 488). Subtract each prime in that list which is less that 488/2 from 488 and check to see if the result is also in the list. If so, it's a solution. There are 10 solutions:





1 + 487


31 + 457


67 + 421


79 + 409


109 + 379


139 + 349


151 + 337


157 + 331


181 + 307


211 + 277



31 and 457.





31 + 457 = 488.





It is not hard (though perhaps a bit tedious) to check that 31 and 457 are, in fact, prime.
11 and 477 works too





(With props. to TheMathemagician)

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