The CAS Registry Mumber 479-99-2 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,7 and 9 respectively; the second part has 2 digits, 9 and 9 respectively. Calculate Digit Verification of CAS Registry Number 479-99: (5*4)+(4*7)+(3*9)+(2*9)+(1*9)=102 102 % 10 = 2 So 479-99-2 is a valid CAS Registry Number.