The CAS Registry Mumber 90589-98-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,5,8 and 9 respectively; the second part has 2 digits, 9 and 8 respectively. Calculate Digit Verification of CAS Registry Number 90589-98: (7*9)+(6*0)+(5*5)+(4*8)+(3*9)+(2*9)+(1*8)=173 173 % 10 = 3 So 90589-98-3 is a valid CAS Registry Number.