The CAS Registry Mumber 112323-80-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,2,3,2 and 3 respectively; the second part has 2 digits, 8 and 0 respectively. Calculate Digit Verification of CAS Registry Number 112323-80: (8*1)+(7*1)+(6*2)+(5*3)+(4*2)+(3*3)+(2*8)+(1*0)=75 75 % 10 = 5 So 112323-80-5 is a valid CAS Registry Number.