The CAS Registry Mumber 72732-47-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,7,3 and 2 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 72732-47: (7*7)+(6*2)+(5*7)+(4*3)+(3*2)+(2*4)+(1*7)=129 129 % 10 = 9 So 72732-47-9 is a valid CAS Registry Number.