The CAS Registry Mumber 138851-34-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,8,5 and 1 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 138851-34: (8*1)+(7*3)+(6*8)+(5*8)+(4*5)+(3*1)+(2*3)+(1*4)=150 150 % 10 = 0 So 138851-34-0 is a valid CAS Registry Number.