The CAS Registry Mumber 109600-96-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,9,6,0 and 0 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 109600-96: (8*1)+(7*0)+(6*9)+(5*6)+(4*0)+(3*0)+(2*9)+(1*6)=116 116 % 10 = 6 So 109600-96-6 is a valid CAS Registry Number.