Last 2 digits are square of 1st digits. Hence 749

Based upon pattern recognition or simply adding 111+2 = 113 and then adding that to the last number in the series 636 = the answer of: 749

It follows the logic below 309 + 107 = 416 416 + 109 = 525 525 + 111 = 636 636 + 113 = 749 The answer is 749

309 416 525 636 Square of first digit is next two digits So ans is 749