The CAS Registry Mumber 4032-53-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,0,3 and 2 respectively; the second part has 2 digits, 5 and 3 respectively. Calculate Digit Verification of CAS Registry Number 4032-53: (6*4)+(5*0)+(4*3)+(3*2)+(2*5)+(1*3)=55 55 % 10 = 5 So 4032-53-5 is a valid CAS Registry Number.