16. The Sum Sn of first 'n' even natural numbers is given by the relat – InterviewSolution

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16. The Sum Sn of first 'n' even natural numbers is given by the relation Sn- nln 1). Find n, ifthe sum is 420.

Answer»

Sn = n(n+1) 420 = n(n+1) 21×20 = n(n+1) n = 20

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