Find the sum of multiples of 7 between 200 and 400
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200/7 = 28.555..
400/7 = 57.14..
So we want sum of 29*7 + 30 * 7 + 31 * 7 + ... + 56*7 + 57 * 7
Sum = 7 * [ 29 + 30 + 31 + ... + 56 + 57 ]
= 7 * (29+57)/2 * (57-29+1) = 8729
400/7 = 57.14..
So we want sum of 29*7 + 30 * 7 + 31 * 7 + ... + 56*7 + 57 * 7
Sum = 7 * [ 29 + 30 + 31 + ... + 56 + 57 ]
= 7 * (29+57)/2 * (57-29+1) = 8729
kvnmurty:
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