Question

Find the wrong term of the series :

$7,15,31,63,126,255,511$

• A. $31$
• B. $63$
• C. $126$
• D. $255$

Answer 1

The correct option is C $126$

Here each of the next number is one more than the twice of previous number.
Clearly, $63\times 2+1=127$ $\ne 126$.
Therefore, $126$ is the wrong term of the series.
Hence, option (C) is the correct answer.