The CAS Registry Mumber 11113-82-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,1,1,1 and 3 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 11113-82: (7*1)+(6*1)+(5*1)+(4*1)+(3*3)+(2*8)+(1*2)=49 49 % 10 = 9 So 11113-82-9 is a valid CAS Registry Number.