The CAS Registry Mumber 55119-66-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,5,1,1 and 9 respectively; the second part has 2 digits, 6 and 6 respectively. Calculate Digit Verification of CAS Registry Number 55119-66: (7*5)+(6*5)+(5*1)+(4*1)+(3*9)+(2*6)+(1*6)=119 119 % 10 = 9 So 55119-66-9 is a valid CAS Registry Number.