The CAS Registry Mumber 18089-10-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,8,0,8 and 9 respectively; the second part has 2 digits, 1 and 0 respectively. Calculate Digit Verification of CAS Registry Number 18089-10: (7*1)+(6*8)+(5*0)+(4*8)+(3*9)+(2*1)+(1*0)=116 116 % 10 = 6 So 18089-10-6 is a valid CAS Registry Number.