The CAS Registry Mumber 75713-44-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,7,1 and 3 respectively; the second part has 2 digits, 4 and 4 respectively. Calculate Digit Verification of CAS Registry Number 75713-44: (7*7)+(6*5)+(5*7)+(4*1)+(3*3)+(2*4)+(1*4)=139 139 % 10 = 9 So 75713-44-9 is a valid CAS Registry Number.