Explanation

The given series is formed by adding 1, 4, 9, 16, 25, and 36 (which are consecutive perfect squares) to the previous term. Breaking it down:

• 1 + 1 = 2
• 2 + 4 = 6
• 6 + 9 = 15
• 15 + 16 = 31
• 31 + 25 = 56

56 + 36 = 92 (not 91)

So, the correct series would be: 1, 2, 6, 15, 31, 56, 92.

Therefore, the wrong number in the series is 91.