Find out the wrong number in the series given below :15, 16, 34, 105, 424, 2124, 12756
A. 34B. 105C. 2124 D. 16
Sol:
2nd term = 1st term × 1 + 1 = 15 × 1 + 1 = 16
3rd term = 2nd term × 2 + 2 = 16 × 2 + 2 = 34
4th term = 3rd term × 3 + 3 = 34 × 3 + 3 = 105
5th term = 4th term × 4 + 4 = 105 × 4 + 4 = 424
6th term = 5th term × 5 + 5 = 424 × 5 + 5 = 2125 ≠ 2124
∴ 2124 is wrong.
