The CAS Registry Mumber 129693-96-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,9,6,9 and 3 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 129693-96: (8*1)+(7*2)+(6*9)+(5*6)+(4*9)+(3*3)+(2*9)+(1*6)=175 175 % 10 = 5 So 129693-96-5 is a valid CAS Registry Number.