The CAS Registry Mumber 132204-66-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,2,2,0 and 4 respectively; the second part has 2 digits, 6 and 6 respectively. Calculate Digit Verification of CAS Registry Number 132204-66: (8*1)+(7*3)+(6*2)+(5*2)+(4*0)+(3*4)+(2*6)+(1*6)=81 81 % 10 = 1 So 132204-66-1 is a valid CAS Registry Number.