The CAS Registry Mumber 51217-96-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,1,2,1 and 7 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 51217-96: (7*5)+(6*1)+(5*2)+(4*1)+(3*7)+(2*9)+(1*6)=100 100 % 10 = 0 So 51217-96-0 is a valid CAS Registry Number.