The CAS Registry Mumber 393-95-3 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 3,9 and 3 respectively; the second part has 2 digits, 9 and 5 respectively. Calculate Digit Verification of CAS Registry Number 393-95: (5*3)+(4*9)+(3*3)+(2*9)+(1*5)=83 83 % 10 = 3 So 393-95-3 is a valid CAS Registry Number.