The CAS Registry Mumber 113317-85-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,3,1 and 7 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 113317-85: (8*1)+(7*1)+(6*3)+(5*3)+(4*1)+(3*7)+(2*8)+(1*5)=94 94 % 10 = 4 So 113317-85-4 is a valid CAS Registry Number.