What is the next number in the sequence 1, 3, 7, 15, 31, 63, ... ?
Answer and explanation
Correct answer: C. 127
- Step 1: The differences are 2, 4, 8, 16, 32, which double each time. Step 2. The next difference is 64, and 63 + 64 = 127. Step 3. The terms are one less than the powers of 2. Answer: 127. Why not the others: 126: This doubles 63. 95: This adds 32 to 63, repeating the earlier size of gap rather than doubling it. 128: This is 2⁷, but the rule is 2ⁿ - 1.
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