Posted by Juniorsbook on Nov 23, 2009 in Optical Illusion | Visually Perceived Image: Question Mark Click here to learn more Answer: 74. Each number is the sum of the number in the previous row plus the product of its digits: 13+ (1*3), 16+ (1*6), 22+ (2*2), 26+ (2*6), 38+ (3*8), 62+ (6*2) =74.