The CAS Registry Mumber 5140-05-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,1,4 and 0 respectively; the second part has 2 digits, 0 and 5 respectively. Calculate Digit Verification of CAS Registry Number 5140-05: (6*5)+(5*1)+(4*4)+(3*0)+(2*0)+(1*5)=56 56 % 10 = 6 So 5140-05-6 is a valid CAS Registry Number.