The CAS Registry Mumber 138008-73-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,0,0 and 8 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 138008-73: (8*1)+(7*3)+(6*8)+(5*0)+(4*0)+(3*8)+(2*7)+(1*3)=118 118 % 10 = 8 So 138008-73-8 is a valid CAS Registry Number.