The CAS Registry Mumber 344244-09-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,4,4,2,4 and 4 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 344244-09: (8*3)+(7*4)+(6*4)+(5*2)+(4*4)+(3*4)+(2*0)+(1*9)=123 123 % 10 = 3 So 344244-09-3 is a valid CAS Registry Number.