The CAS Registry Mumber 139254-38-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,9,2,5 and 4 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 139254-38: (8*1)+(7*3)+(6*9)+(5*2)+(4*5)+(3*4)+(2*3)+(1*8)=139 139 % 10 = 9 So 139254-38-9 is a valid CAS Registry Number.