The CAS Registry Mumber 11115-85-8 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 5 respectively. Calculate Digit Verification of CAS Registry Number 11115-85: (7*1)+(6*1)+(5*1)+(4*1)+(3*5)+(2*8)+(1*5)=58 58 % 10 = 8 So 11115-85-8 is a valid CAS Registry Number.