The CAS Registry Mumber 118326-91-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,8,3,2 and 6 respectively; the second part has 2 digits, 9 and 1 respectively. Calculate Digit Verification of CAS Registry Number 118326-91: (8*1)+(7*1)+(6*8)+(5*3)+(4*2)+(3*6)+(2*9)+(1*1)=123 123 % 10 = 3 So 118326-91-3 is a valid CAS Registry Number.