The CAS Registry Mumber 4628-85-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,6,2 and 8 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 4628-85: (6*4)+(5*6)+(4*2)+(3*8)+(2*8)+(1*5)=107 107 % 10 = 7 So 4628-85-7 is a valid CAS Registry Number.