The CAS Registry Mumber 11115-83-6 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 5 respectively; the second part has 2 digits, 8 and 3 respectively. Calculate Digit Verification of CAS Registry Number 11115-83: (7*1)+(6*1)+(5*1)+(4*1)+(3*5)+(2*8)+(1*3)=56 56 % 10 = 6 So 11115-83-6 is a valid CAS Registry Number.