What is the next number in the sequence 3, 6, 5, 10, 9, 18, 17, ... ?

Answer and explanation

Correct answer: A. 34

  1. Step 1: The rule alternates: double, then subtract 1. Step 2. 3 × 2 = 6, 6 - 1 = 5, 5 × 2 = 10, 10 - 1 = 9, 9 × 2 = 18, 18 - 1 = 17. Step 3. The next step is double: 17 × 2 = 34. Answer: 34. Why not the others: 16: This subtracts 1 again instead of doubling. 18: This adds 1 instead of doubling. 33: This doubles and subtracts 1 in the same step.

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