The CAS Registry Mumber 137119-66-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,7,1,1 and 9 respectively; the second part has 2 digits, 6 and 6 respectively. Calculate Digit Verification of CAS Registry Number 137119-66: (8*1)+(7*3)+(6*7)+(5*1)+(4*1)+(3*9)+(2*6)+(1*6)=125 125 % 10 = 5 So 137119-66-5 is a valid CAS Registry Number.