The CAS Registry Mumber 72333-96-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,3,3 and 3 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 72333-96: (7*7)+(6*2)+(5*3)+(4*3)+(3*3)+(2*9)+(1*6)=121 121 % 10 = 1 So 72333-96-1 is a valid CAS Registry Number.