Question

Find out the wrong number in the series given below :
$15,16,34,105,424,2124,12756$

• A. $34$
• B. $105$
• C. $2124$
• D. $16$

Answer 1

The correct option is C $2124$

$\text{2nd term}=\text{1st term}\times 1+1=15\times 1+1=16$
$\text{3rd term}=\text{2nd term}\times 2+2=16\times 2+2=34$
$\text{4th term}=\text{3rd term}\times 3+3=34\times 3+3=105$
$\text{5th term}=\text{4th term}\times 4+4=105\times 4+4=424$
$\text{6th term}=\text{5th term}\times 5+5=424\times 5+5=2125\ne 2124$
$\therefore 2124$ is wrong.