The CAS Registry Mumber 57713-38-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,7,1 and 3 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 57713-38: (7*5)+(6*7)+(5*7)+(4*1)+(3*3)+(2*3)+(1*8)=139 139 % 10 = 9 So 57713-38-9 is a valid CAS Registry Number.