The CAS Registry Mumber 109114-55-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,9,1,1 and 4 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 109114-55: (8*1)+(7*0)+(6*9)+(5*1)+(4*1)+(3*4)+(2*5)+(1*5)=98 98 % 10 = 8 So 109114-55-8 is a valid CAS Registry Number.