The CAS Registry Mumber 128921-96-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,8,9,2 and 1 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 128921-96: (8*1)+(7*2)+(6*8)+(5*9)+(4*2)+(3*1)+(2*9)+(1*6)=150 150 % 10 = 0 So 128921-96-0 is a valid CAS Registry Number.