The CAS Registry Mumber 99289-41-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,9,2,8 and 9 respectively; the second part has 2 digits, 4 and 1 respectively. Calculate Digit Verification of CAS Registry Number 99289-41: (7*9)+(6*9)+(5*2)+(4*8)+(3*9)+(2*4)+(1*1)=195 195 % 10 = 5 So 99289-41-5 is a valid CAS Registry Number.