The CAS Registry Mumber 457-43-2 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,5 and 7 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 457-43: (5*4)+(4*5)+(3*7)+(2*4)+(1*3)=72 72 % 10 = 2 So 457-43-2 is a valid CAS Registry Number.