The CAS Registry Mumber 103981-95-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,3,9,8 and 1 respectively; the second part has 2 digits, 9 and 5 respectively. Calculate Digit Verification of CAS Registry Number 103981-95: (8*1)+(7*0)+(6*3)+(5*9)+(4*8)+(3*1)+(2*9)+(1*5)=129 129 % 10 = 9 So 103981-95-9 is a valid CAS Registry Number.