The CAS Registry Mumber 98236-89-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,8,2,3 and 6 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 98236-89: (7*9)+(6*8)+(5*2)+(4*3)+(3*6)+(2*8)+(1*9)=176 176 % 10 = 6 So 98236-89-6 is a valid CAS Registry Number.