The CAS Registry Mumber 9083-71-0 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 9,0,8 and 3 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 9083-71: (6*9)+(5*0)+(4*8)+(3*3)+(2*7)+(1*1)=110 110 % 10 = 0 So 9083-71-0 is a valid CAS Registry Number.