The CAS Registry Mumber 139004-16-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,9,0,0 and 4 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 139004-16: (8*1)+(7*3)+(6*9)+(5*0)+(4*0)+(3*4)+(2*1)+(1*6)=103 103 % 10 = 3 So 139004-16-3 is a valid CAS Registry Number.