The CAS Registry Mumber 11144-18-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,1,1,4 and 4 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 11144-18: (7*1)+(6*1)+(5*1)+(4*4)+(3*4)+(2*1)+(1*8)=56 56 % 10 = 6 So 11144-18-6 is a valid CAS Registry Number.