The CAS Registry Mumber 132351-20-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,2,3,5 and 1 respectively; the second part has 2 digits, 2 and 0 respectively. Calculate Digit Verification of CAS Registry Number 132351-20: (8*1)+(7*3)+(6*2)+(5*3)+(4*5)+(3*1)+(2*2)+(1*0)=83 83 % 10 = 3 So 132351-20-3 is a valid CAS Registry Number.