The CAS Registry Mumber 83081-92-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,0,8 and 1 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 83081-92: (7*8)+(6*3)+(5*0)+(4*8)+(3*1)+(2*9)+(1*2)=129 129 % 10 = 9 So 83081-92-9 is a valid CAS Registry Number.