Multiple choice

Find the wrong number in the given sequence. 3, 4, 13, 38, 87, 166, 289

  1. 38

  2. 13

  3. 87

  4. 166

  5. 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Differences: 4-3=1, 13-4=9, 38-13=25, 87-38=49, 166-87=79, 289-166=123. The differences are squares: 1^2, 3^2, 5^2, 7^2. The next difference should be 9^2 = 81. 87 + 81 = 168. The next should be 11^2 = 121. 168 + 121 = 289. Thus, 166 is the wrong number.

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