The CAS Registry Mumber 4101-04-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,1,0 and 1 respectively; the second part has 2 digits, 0 and 4 respectively. Calculate Digit Verification of CAS Registry Number 4101-04: (6*4)+(5*1)+(4*0)+(3*1)+(2*0)+(1*4)=36 36 % 10 = 6 So 4101-04-6 is a valid CAS Registry Number.