The CAS Registry Mumber 502-63-6 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 5,0 and 2 respectively; the second part has 2 digits, 6 and 3 respectively. Calculate Digit Verification of CAS Registry Number 502-63: (5*5)+(4*0)+(3*2)+(2*6)+(1*3)=46 46 % 10 = 6 So 502-63-6 is a valid CAS Registry Number.