Multiple choice

Find the missing number in the given series. 8, 5, 6, 10, 21, ?

  1. 52

  2. 52.5

  3. 53

  4. 53.5

  5. 64
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pattern is: multiply by 0.5, add 0.5; multiply by 1, add 1; multiply by 1.5, add 1.5; multiply by 2, add 2. Following this: 8 × 0.5 = 4, 4 + 0.5 = 4.5 (but we have 5, so adjusted); 5 × 1 = 5, 5 + 1 = 6; 6 × 1.5 = 9, 9 + 1 = 10; 10 × 2 = 20, 20 + 1 = 21; 21 × 2.5 = 52.5, 52.5 + 1 = 53.5. The pattern uses increasing multipliers (0.5, 1, 1.5, 2, 2.5) with additions of 0.5, 1, 1, 1, 1. The answer 53.5 fits.

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