The CAS Registry Mumber 159518-86-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,9,5,1 and 8 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 159518-86: (8*1)+(7*5)+(6*9)+(5*5)+(4*1)+(3*8)+(2*8)+(1*6)=172 172 % 10 = 2 So 159518-86-2 is a valid CAS Registry Number.