The CAS Registry Mumber 54129-03-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,4,1,2 and 9 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 54129-03: (7*5)+(6*4)+(5*1)+(4*2)+(3*9)+(2*0)+(1*3)=102 102 % 10 = 2 So 54129-03-2 is a valid CAS Registry Number.