The CAS Registry Mumber 13013-15-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,3,0,1 and 3 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 13013-15: (7*1)+(6*3)+(5*0)+(4*1)+(3*3)+(2*1)+(1*5)=45 45 % 10 = 5 So 13013-15-5 is a valid CAS Registry Number.