The CAS Registry Mumber 155473-75-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,5,4,7 and 3 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 155473-75: (8*1)+(7*5)+(6*5)+(5*4)+(4*7)+(3*3)+(2*7)+(1*5)=149 149 % 10 = 9 So 155473-75-9 is a valid CAS Registry Number.