The CAS Registry Mumber 51218-04-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,1,2,1 and 8 respectively; the second part has 2 digits, 0 and 4 respectively. Calculate Digit Verification of CAS Registry Number 51218-04: (7*5)+(6*1)+(5*2)+(4*1)+(3*8)+(2*0)+(1*4)=83 83 % 10 = 3 So 51218-04-3 is a valid CAS Registry Number.