The CAS Registry Mumber 129191-02-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,9,1,9 and 1 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 129191-02: (8*1)+(7*2)+(6*9)+(5*1)+(4*9)+(3*1)+(2*0)+(1*2)=122 122 % 10 = 2 So 129191-02-2 is a valid CAS Registry Number.