The CAS Registry Mumber 2419-44-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,4,1 and 9 respectively; the second part has 2 digits, 4 and 4 respectively. Calculate Digit Verification of CAS Registry Number 2419-44: (6*2)+(5*4)+(4*1)+(3*9)+(2*4)+(1*4)=75 75 % 10 = 5 So 2419-44-5 is a valid CAS Registry Number.