Multiple choice

Choose the correct alternative from the given ones that will complete the series. 1780, 939, ?, 121, 0

  1. 400

  2. 410

  3. 390

  4. 389
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pattern is subtract 479, then subtract 529, then subtract 579 (difference increases by 50 each time). 1780-479=1301, 939-529=410, 410-579=-169 (but next is 121). Let me recalculate: The actual pattern is: subtract 841 (1780-939=841), then 939-410=529, then 410-121=289, then 121-0=121. The differences are 29², 23², 17², 11² - decreasing by 6² each time (29-23=6, 23-17=6, 17-11=6).

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