The CAS Registry Mumber 483-81-8 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,8 and 3 respectively; the second part has 2 digits, 8 and 1 respectively. Calculate Digit Verification of CAS Registry Number 483-81: (5*4)+(4*8)+(3*3)+(2*8)+(1*1)=78 78 % 10 = 8 So 483-81-8 is a valid CAS Registry Number.