The CAS Registry Mumber 62571-55-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,2,5,7 and 1 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 62571-55: (7*6)+(6*2)+(5*5)+(4*7)+(3*1)+(2*5)+(1*5)=125 125 % 10 = 5 So 62571-55-5 is a valid CAS Registry Number.