The CAS Registry Mumber 393-46-4 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, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 393-46: (5*3)+(4*9)+(3*3)+(2*4)+(1*6)=74 74 % 10 = 4 So 393-46-4 is a valid CAS Registry Number.