The CAS Registry Mumber 33832-21-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,3,8,3 and 2 respectively; the second part has 2 digits, 2 and 1 respectively. Calculate Digit Verification of CAS Registry Number 33832-21: (7*3)+(6*3)+(5*8)+(4*3)+(3*2)+(2*2)+(1*1)=102 102 % 10 = 2 So 33832-21-2 is a valid CAS Registry Number.