The CAS Registry Mumber 5502-67-0 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,5,0 and 2 respectively; the second part has 2 digits, 6 and 7 respectively. Calculate Digit Verification of CAS Registry Number 5502-67: (6*5)+(5*5)+(4*0)+(3*2)+(2*6)+(1*7)=80 80 % 10 = 0 So 5502-67-0 is a valid CAS Registry Number.