Multiple choice

Directions: Find the wrong number in the following series. 40 120 240 720 1400 4320 8640

  1. 120

  2. 240

  3. 720

  4. 1400
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pattern is multiplication by 3, 2, 3, 2, 3, 2. 40 * 3 = 120, 120 * 2 = 240, 240 * 3 = 720, 720 * 2 = 1440 (not 1400), 1440 * 3 = 4320, 4320 * 2 = 8640. 1400 is the wrong number.

AI explanation

The series follows a pattern of alternately multiplying by 3 and 2: 40 x 3 = 120, 120 x 2 = 240, 240 x 3 = 720 and 720 x 2 = 1440. The fifth term should be 1440 instead of 1400, so the wrong number is 1400.

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