Aptitude | Arithmetic Aptitude 4 | Question 3

7 + 7² + 7³………..7⁶ =?

(A) 140136
(B) 142156
(C) 133256
(D) 137256

Answer: (D)
Explanation:

Given series is a G. P. with a = 7, r = 7 and n = 6

∴ Sn = a(rn-1) / (r-1)

∴ Sn = 7(76-1) / 6

  Sn = = 137256

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