Multiple choice

Find the wrong number in the following series. 1 3 7 15 33 63 127

  1. 3

  2. 7

  3. 15

  4. 33
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pattern is 2^n - 1. 2^1-1=1, 2^2-1=3, 2^3-1=7, 2^4-1=15, 2^5-1=31, 2^6-1=63, 2^7-1=127. The number 33 is incorrect; it should be 31.

AI explanation

The pattern follows the logic of multiplying by 2 and then adding 1. Applying this, 1 times 2 plus 1 is 3, 3 times 2 plus 1 is 7, 7 times 2 plus 1 is 15, and 15 times 2 plus 1 is 31. Following this established rule, the number 33 is the incorrect term in the series.

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