The CAS Registry Mumber 117169-36-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,7,1,6 and 9 respectively; the second part has 2 digits, 3 and 6 respectively. Calculate Digit Verification of CAS Registry Number 117169-36: (8*1)+(7*1)+(6*7)+(5*1)+(4*6)+(3*9)+(2*3)+(1*6)=125 125 % 10 = 5 So 117169-36-5 is a valid CAS Registry Number.