first number is 5.
second is 5 + (4 2) = 5 + 8 = 13
third is 5 + (4 2) (4 3) = 5 + 8 + 12 = 25
fourth is 5 + (4 2) (4 3) + (4 4) = 5 + 8 + 12 + 16 = 41
fifth is 5 + (4 2) (4 3) + (4 4) + (4 5) = 5 + 8 + 12 + 16 + 20 = 61
sixth is 5 + (4 2) (4 3) + (4 4) + (4 5) + (4 * 6) = 5 + 8 + 12 + 16 + 20 + 24 = 85
So missing number is 41
