Multiple choice

Directions: Find the missing number in the following series. 210, 21, 189, ?, 170.1, 17.01

  1. 18.9

  2. 56

  3. 71.1

  4. 92

  5. 108.7
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A Correct answer
Explanation

The pattern is divide by 10, then multiply by 9. 210 / 10 = 21. 21 * 9 = 189. 189 / 10 = 18.9. 18.9 * 9 = 170.1. 170.1 / 10 = 17.01.

AI explanation

The series alternates by dividing by 10 and subtracting 21. Dividing 210 by 10 gives 21, and subtracting 21 from 21 gives 0. Since subtracting 21 from 189 gives 168, which is not in the options, the pattern alternates between dividing by 10 and multiplying by 9. Multiplying 21 by 9 gives 189, and multiplying 170.1 by 10 gives 170.1. Therefore, dividing 189 by 10 gives 18.9.

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