The CAS Registry Mumber 13612-55-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,3,6,1 and 2 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 13612-55: (7*1)+(6*3)+(5*6)+(4*1)+(3*2)+(2*5)+(1*5)=80 80 % 10 = 0 So 13612-55-0 is a valid CAS Registry Number.