The CAS Registry Mumber 75473-16-4 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, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 75473-16: (7*7)+(6*5)+(5*4)+(4*7)+(3*3)+(2*1)+(1*6)=144 144 % 10 = 4 So 75473-16-4 is a valid CAS Registry Number.