The CAS Registry Mumber 81198-32-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,1,1,9 and 8 respectively; the second part has 2 digits, 3 and 2 respectively. Calculate Digit Verification of CAS Registry Number 81198-32: (7*8)+(6*1)+(5*1)+(4*9)+(3*8)+(2*3)+(1*2)=135 135 % 10 = 5 So 81198-32-5 is a valid CAS Registry Number.