The CAS Registry Mumber 112347-34-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,2,3,4 and 7 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 112347-34: (8*1)+(7*1)+(6*2)+(5*3)+(4*4)+(3*7)+(2*3)+(1*4)=89 89 % 10 = 9 So 112347-34-9 is a valid CAS Registry Number.