Multiple choice

In the following number series, one term does not fit into the series. Find the wrong term. $3 ,4, 15, 16, 25, 36, 63, 64.....$

  1. $15$
  2. $16$
  3. $25$
  4. $36$
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C Correct answer
Explanation

The series is squares: 2^2=4, 4^2=16, 5^2=25, 6^2=36, 8^2=64. The sequence is 3, 4, 15, 16, 25, 36, 63, 64. The numbers 4, 16, 25, 36, 64 are squares. 15 and 63 are not. 25 is a square, but the pattern is alternating between squares and non-squares.

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