The CAS Registry Mumber 23293-23-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,3,2,9 and 3 respectively; the second part has 2 digits, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 23293-23: (7*2)+(6*3)+(5*2)+(4*9)+(3*3)+(2*2)+(1*3)=94 94 % 10 = 4 So 23293-23-4 is a valid CAS Registry Number.