The CAS Registry Mumber 98891-39-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,8,8,9 and 1 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 98891-39: (7*9)+(6*8)+(5*8)+(4*9)+(3*1)+(2*3)+(1*9)=205 205 % 10 = 5 So 98891-39-5 is a valid CAS Registry Number.