The CAS Registry Mumber 18111-19-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,8,1,1 and 1 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 18111-19: (7*1)+(6*8)+(5*1)+(4*1)+(3*1)+(2*1)+(1*9)=78 78 % 10 = 8 So 18111-19-8 is a valid CAS Registry Number.