The CAS Registry Mumber 72438-03-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,4,3 and 8 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 72438-03: (7*7)+(6*2)+(5*4)+(4*3)+(3*8)+(2*0)+(1*3)=120 120 % 10 = 0 So 72438-03-0 is a valid CAS Registry Number.