The CAS Registry Mumber 1189106-89-5 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,1,8,9,1,0 and 6 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 1189106-89: (9*1)+(8*1)+(7*8)+(6*9)+(5*1)+(4*0)+(3*6)+(2*8)+(1*9)=175 175 % 10 = 5 So 1189106-89-5 is a valid CAS Registry Number.