The CAS Registry Mumber 133230-52-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,3,2,3 and 0 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 133230-52: (8*1)+(7*3)+(6*3)+(5*2)+(4*3)+(3*0)+(2*5)+(1*2)=81 81 % 10 = 1 So 133230-52-1 is a valid CAS Registry Number.