The CAS Registry Mumber 11118-73-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,1,1,1 and 8 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 11118-73: (7*1)+(6*1)+(5*1)+(4*1)+(3*8)+(2*7)+(1*3)=63 63 % 10 = 3 So 11118-73-3 is a valid CAS Registry Number.