The CAS Registry Mumber 117135-79-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,7,1,3 and 5 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 117135-79: (8*1)+(7*1)+(6*7)+(5*1)+(4*3)+(3*5)+(2*7)+(1*9)=112 112 % 10 = 2 So 117135-79-2 is a valid CAS Registry Number.