The CAS Registry Mumber 133214-28-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,3,2,1 and 4 respectively; the second part has 2 digits, 2 and 8 respectively. Calculate Digit Verification of CAS Registry Number 133214-28: (8*1)+(7*3)+(6*3)+(5*2)+(4*1)+(3*4)+(2*2)+(1*8)=85 85 % 10 = 5 So 133214-28-5 is a valid CAS Registry Number.