The CAS Registry Mumber 13940-86-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,3,9,4 and 0 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 13940-86: (7*1)+(6*3)+(5*9)+(4*4)+(3*0)+(2*8)+(1*6)=108 108 % 10 = 8 So 13940-86-8 is a valid CAS Registry Number.