The CAS Registry Mumber 139683-46-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,9,6,8 and 3 respectively; the second part has 2 digits, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 139683-46: (8*1)+(7*3)+(6*9)+(5*6)+(4*8)+(3*3)+(2*4)+(1*6)=168 168 % 10 = 8 So 139683-46-8 is a valid CAS Registry Number.