The CAS Registry Mumber 1334591-03-5 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,3,3,4,5,9 and 1 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 1334591-03: (9*1)+(8*3)+(7*3)+(6*4)+(5*5)+(4*9)+(3*1)+(2*0)+(1*3)=145 145 % 10 = 5 So 1334591-03-5 is a valid CAS Registry Number.