Multiple choice general knowledge math & puzzles

6, 9, 15, 21, 24, 28, 30

  1. 28

  2. 21

  3. 24

  4. 30
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The number 28 is the only perfect number in this sequence (a perfect number equals the sum of its proper divisors: 1+2+4+7+14=28). The other numbers (6, 9, 15, 21, 24, 30) are not perfect numbers. This identifies 28 as the unique element.

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