Answer : 2 28 Explanation : Answer: B) 28 Explanation: Here the given series 1, 6, ?, 15, 45, 66, 91 follows aPattern in the series is, 5, 9, 13,...,.. 21, 25So 4 is getting increased at every term addition.Missing Number in the series will be 15 (9 4) = 15 13 = 28.

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