The CAS Registry Mumber 4505-08-2 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,5,0 and 5 respectively; the second part has 2 digits, 0 and 8 respectively. Calculate Digit Verification of CAS Registry Number 4505-08: (6*4)+(5*5)+(4*0)+(3*5)+(2*0)+(1*8)=72 72 % 10 = 2 So 4505-08-2 is a valid CAS Registry Number.