The CAS Registry Mumber 133321-47-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,3,3,2 and 1 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 133321-47: (8*1)+(7*3)+(6*3)+(5*3)+(4*2)+(3*1)+(2*4)+(1*7)=88 88 % 10 = 8 So 133321-47-8 is a valid CAS Registry Number.