The CAS Registry Mumber 447-45-0 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,4 and 7 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 447-45: (5*4)+(4*4)+(3*7)+(2*4)+(1*5)=70 70 % 10 = 0 So 447-45-0 is a valid CAS Registry Number.