The CAS Registry Mumber 129169-85-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,9,1,6 and 9 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 129169-85: (8*1)+(7*2)+(6*9)+(5*1)+(4*6)+(3*9)+(2*8)+(1*5)=153 153 % 10 = 3 So 129169-85-3 is a valid CAS Registry Number.