The CAS Registry Mumber 75473-31-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,4,7 and 3 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 75473-31: (7*7)+(6*5)+(5*4)+(4*7)+(3*3)+(2*3)+(1*1)=143 143 % 10 = 3 So 75473-31-3 is a valid CAS Registry Number.