The CAS Registry Mumber 266693-93-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,6,6,6,9 and 3 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 266693-93: (8*2)+(7*6)+(6*6)+(5*6)+(4*9)+(3*3)+(2*9)+(1*3)=190 190 % 10 = 0 So 266693-93-0 is a valid CAS Registry Number.