Multiple choice general knowledge math & puzzles

find the odd one in the following series. 1,9,36,100,225,440,...

  1. 36

  2. 100

  3. 440

  4. 225
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C Correct answer
Explanation

The series is: 1=1^2, 9=3^2, 36=6^2, 100=10^2, 225=15^2. The base numbers increase by: 3-1=2, 6-3=3, 10-6=4, 15-10=5. Following this pattern, the next base should be 15+6=21, and 21^2=441, not 440. 440 is the wrong number in the sequence.

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