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Even multiples of 15

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by bluementor » Thu May 21, 2009 5:25 am
the smallest even multiple of 15 between 295 and 615 is 300.
the largest even multiple of 15 between 295 and 615 is 600.

the distance between every even multiple of 15 is 30.

between 300 and 600, inclusive, there are (600 - 300)/30 + 1 = 11 even multiples of 30.

k = (11/2)*(300 + 600)
k = 5.5*100*9
k = 55*10*9
k = 11*5*5*2*3*3

therefore, the largest prime factor of k is 11.

choose c.

-BM-
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