The CAS Registry Mumber 128457-96-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,8,4,5 and 7 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 128457-96: (8*1)+(7*2)+(6*8)+(5*4)+(4*5)+(3*7)+(2*9)+(1*6)=155 155 % 10 = 5 So 128457-96-5 is a valid CAS Registry Number.