The CAS Registry Mumber 89393-28-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,9,3,9 and 3 respectively; the second part has 2 digits, 2 and 8 respectively. Calculate Digit Verification of CAS Registry Number 89393-28: (7*8)+(6*9)+(5*3)+(4*9)+(3*3)+(2*2)+(1*8)=182 182 % 10 = 2 So 89393-28-2 is a valid CAS Registry Number.