Multiple choice general knowledge math & puzzles

Odd One Out means find the number which is different to other numbers--- 15,55,120,210,310

  1. 55

  2. 310

  3. 120

  4. 210
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The sequence 15, 55, 120, 210 follows the pattern n(n+1)/2 where n increases by 5: 5×6/2=15, 10×11/2=55, 15×16/2=120, 20×21/2=210. The next term should be 25×26/2=325, not 310. Alternatively, 310 doesn't fit the triangular number pattern.

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