The CAS Registry Mumber 53789-72-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,3,7,8 and 9 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 53789-72: (7*5)+(6*3)+(5*7)+(4*8)+(3*9)+(2*7)+(1*2)=163 163 % 10 = 3 So 53789-72-3 is a valid CAS Registry Number.