The CAS Registry Mumber 133214-31-0 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, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 133214-31: (8*1)+(7*3)+(6*3)+(5*2)+(4*1)+(3*4)+(2*3)+(1*1)=80 80 % 10 = 0 So 133214-31-0 is a valid CAS Registry Number.