The CAS Registry Mumber 135119-51-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,5,1,1 and 9 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 135119-51: (8*1)+(7*3)+(6*5)+(5*1)+(4*1)+(3*9)+(2*5)+(1*1)=106 106 % 10 = 6 So 135119-51-6 is a valid CAS Registry Number.