The CAS Registry Mumber 933673-43-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 9,3,3,6,7 and 3 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 933673-43: (8*9)+(7*3)+(6*3)+(5*6)+(4*7)+(3*3)+(2*4)+(1*3)=189 189 % 10 = 9 So 933673-43-9 is a valid CAS Registry Number.