The CAS Registry Mumber 79344-03-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,9,3,4 and 4 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 79344-03: (7*7)+(6*9)+(5*3)+(4*4)+(3*4)+(2*0)+(1*3)=149 149 % 10 = 9 So 79344-03-9 is a valid CAS Registry Number.