The CAS Registry Mumber 59098-88-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,9,0,9 and 8 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 59098-88: (7*5)+(6*9)+(5*0)+(4*9)+(3*8)+(2*8)+(1*8)=173 173 % 10 = 3 So 59098-88-3 is a valid CAS Registry Number.