The CAS Registry Mumber 138608-19-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,6,0 and 8 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 138608-19: (8*1)+(7*3)+(6*8)+(5*6)+(4*0)+(3*8)+(2*1)+(1*9)=142 142 % 10 = 2 So 138608-19-2 is a valid CAS Registry Number.