The CAS Registry Mumber 5374-05-0 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,3,7 and 4 respectively; the second part has 2 digits, 0 and 5 respectively. Calculate Digit Verification of CAS Registry Number 5374-05: (6*5)+(5*3)+(4*7)+(3*4)+(2*0)+(1*5)=90 90 % 10 = 0 So 5374-05-0 is a valid CAS Registry Number.