The CAS Registry Mumber 97308-38-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,7,3,0 and 8 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 97308-38: (7*9)+(6*7)+(5*3)+(4*0)+(3*8)+(2*3)+(1*8)=158 158 % 10 = 8 So 97308-38-8 is a valid CAS Registry Number.