The CAS Registry Mumber 193696-30-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,9,3,6,9 and 6 respectively; the second part has 2 digits, 3 and 0 respectively. Calculate Digit Verification of CAS Registry Number 193696-30: (8*1)+(7*9)+(6*3)+(5*6)+(4*9)+(3*6)+(2*3)+(1*0)=179 179 % 10 = 9 So 193696-30-9 is a valid CAS Registry Number.