The CAS Registry Mumber 74708-73-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,7,0 and 8 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 74708-73: (7*7)+(6*4)+(5*7)+(4*0)+(3*8)+(2*7)+(1*3)=149 149 % 10 = 9 So 74708-73-9 is a valid CAS Registry Number.