The CAS Registry Mumber 82191-12-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,1,9 and 1 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 82191-12: (7*8)+(6*2)+(5*1)+(4*9)+(3*1)+(2*1)+(1*2)=116 116 % 10 = 6 So 82191-12-6 is a valid CAS Registry Number.