Multiple choice general knowledge math & puzzles

guess the next number in this series: 827, 21, 12, 6, 3, 5

  1. 7

  2. 9

  3. 2

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

The pattern is: add the digits, multiply by 2. 8+2+7=17, 1+7=8, 8×2=16, 1+6=7, 7×2=14, 1+4=5, 5×2=10, 1+0=1, 1×2=2 doesn't match. Alternative: 827→8+2+7=17→1+7=8, 8×2+5=21, 2+1=3→3×4=12, 1+2=3→3×2=6, 6÷2=3, 3-2=1, 1×5=5. Pattern: sum digits, operations alternate. Next: 5→5-1=4.

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