The CAS Registry Mumber 100189-40-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,0,1,8 and 9 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 100189-40: (8*1)+(7*0)+(6*0)+(5*1)+(4*8)+(3*9)+(2*4)+(1*0)=80 80 % 10 = 0 So 100189-40-0 is a valid CAS Registry Number.