The CAS Registry Mumber 39031-13-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,9,0,3 and 1 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 39031-13: (7*3)+(6*9)+(5*0)+(4*3)+(3*1)+(2*1)+(1*3)=95 95 % 10 = 5 So 39031-13-5 is a valid CAS Registry Number.