The CAS Registry Mumber 1415668-79-9 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,4,1,5,6,6 and 8 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 1415668-79: (9*1)+(8*4)+(7*1)+(6*5)+(5*6)+(4*6)+(3*8)+(2*7)+(1*9)=179 179 % 10 = 9 So 1415668-79-9 is a valid CAS Registry Number.