The CAS Registry Mumber 93666-92-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,3,6,6 and 6 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 93666-92: (7*9)+(6*3)+(5*6)+(4*6)+(3*6)+(2*9)+(1*2)=173 173 % 10 = 3 So 93666-92-3 is a valid CAS Registry Number.