The CAS Registry Mumber 93745-28-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,3,7,4 and 5 respectively; the second part has 2 digits, 2 and 8 respectively. Calculate Digit Verification of CAS Registry Number 93745-28: (7*9)+(6*3)+(5*7)+(4*4)+(3*5)+(2*2)+(1*8)=159 159 % 10 = 9 So 93745-28-9 is a valid CAS Registry Number.