The CAS Registry Mumber 52328-28-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,2,3,2 and 8 respectively; the second part has 2 digits, 2 and 8 respectively. Calculate Digit Verification of CAS Registry Number 52328-28: (7*5)+(6*2)+(5*3)+(4*2)+(3*8)+(2*2)+(1*8)=106 106 % 10 = 6 So 52328-28-6 is a valid CAS Registry Number.