Multiple choice

In the following number series, a wrong number is given. Find out that wrong number. 42 20 9 3.5 0.70 -0.625

  1. -0.625

  2. 9

  3. 3.5

  4. 0.70

  5. 42
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pattern is (÷2 - 1, ÷2 - 0.5, ÷2 - 0.25, ÷2 - 0.125): 42÷2-1=20 ✓, 20÷2-0.5=9.5 (not 9), 9÷2-0.25=4.25 (not 3.5). The subtraction amounts halve each time. Another view: pattern alternates ÷2-1, ÷2-0.5, ÷2-0.25. From 42: 42÷2-1=20 ✓, 20÷2-0.5=9.5, but 9 is given. From 9: 9÷2-0.25=4.25, but 3.5 is given. Neither fits. The answer claims 0.70 is wrong.

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