Multiple choice

In the following number series, a number is missing. Find out the missing number. 122, 213, 340, 509, 726, ?

  1. 942

  2. 997

  3. 919

  4. 950

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pattern follows the formula n³ - n for consecutive natural numbers starting from 5: 5³-5=125-5=120 (but series shows 122, not matching), 6³-6=216-6=210 (series shows 213), 7³-7=343-7=336 (series shows 340), 8³-8=512-8=504 (series shows 509), 9³-9=729-9=720 (series shows 726). The actual pattern is: differences increase by 26, 38, 54, 74, 100. These are (5²+1), (6²+2), (7²+5), (8²+10), (9²+19). This is inconsistent. Better pattern: each term is (position+4)³ - (position+4) plus increasing values: 122 = 5³-3, 213 = 6³-3, 340 = 7³-3, 509 = 8³-3, 726 = 9³-3. Next: 10³-3 = 1000-3 = 997. Answer is 997 (Option B).

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