The CAS Registry Mumber 40018-11-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,0,0,1 and 8 respectively; the second part has 2 digits, 1 and 1 respectively. Calculate Digit Verification of CAS Registry Number 40018-11: (7*4)+(6*0)+(5*0)+(4*1)+(3*8)+(2*1)+(1*1)=59 59 % 10 = 9 So 40018-11-9 is a valid CAS Registry Number.