The CAS Registry Mumber 114491-66-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,4,4,9 and 1 respectively; the second part has 2 digits, 6 and 6 respectively. Calculate Digit Verification of CAS Registry Number 114491-66: (8*1)+(7*1)+(6*4)+(5*4)+(4*9)+(3*1)+(2*6)+(1*6)=116 116 % 10 = 6 So 114491-66-6 is a valid CAS Registry Number.