The CAS Registry Mumber 139081-15-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,9,0,8 and 1 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 139081-15: (8*1)+(7*3)+(6*9)+(5*0)+(4*8)+(3*1)+(2*1)+(1*5)=125 125 % 10 = 5 So 139081-15-5 is a valid CAS Registry Number.