The CAS Registry Mumber 115368-13-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,5,3,6 and 8 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 115368-13: (8*1)+(7*1)+(6*5)+(5*3)+(4*6)+(3*8)+(2*1)+(1*3)=113 113 % 10 = 3 So 115368-13-3 is a valid CAS Registry Number.