The CAS Registry Mumber 55027-62-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,5,0,2 and 7 respectively; the second part has 2 digits, 6 and 2 respectively. Calculate Digit Verification of CAS Registry Number 55027-62: (7*5)+(6*5)+(5*0)+(4*2)+(3*7)+(2*6)+(1*2)=108 108 % 10 = 8 So 55027-62-8 is a valid CAS Registry Number.