The CAS Registry Mumber 196303-33-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,9,6,3,0 and 3 respectively; the second part has 2 digits, 3 and 3 respectively. Calculate Digit Verification of CAS Registry Number 196303-33: (8*1)+(7*9)+(6*6)+(5*3)+(4*0)+(3*3)+(2*3)+(1*3)=140 140 % 10 = 0 So 196303-33-0 is a valid CAS Registry Number.