The CAS Registry Mumber 117144-75-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,7,1,4 and 4 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 117144-75: (8*1)+(7*1)+(6*7)+(5*1)+(4*4)+(3*4)+(2*7)+(1*5)=109 109 % 10 = 9 So 117144-75-9 is a valid CAS Registry Number.