Multiple choice

Directions: Find the missing term in the following series. 21, 23, 49, 151, ?

  1. 217

  2. 432

  3. 543

  4. 609

  5. 623
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D Correct answer
Explanation

The pattern is: 21 * 1 + 2 = 23; 23 * 2 + 3 = 49; 49 * 3 + 4 = 151; 151 * 4 + 5 = 609.

AI explanation

The pattern is to multiply the previous term by 1, 2, and 3 respectively, and then add 2, 3, and 4 respectively. So, 21 times 1 plus 2 is 23, 23 times 2 plus 3 is 49, and 49 times 3 plus 4 is 151. Applying this to the last term, 151 times 4 plus 5 equals 609.

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