The CAS Registry Mumber 65259-97-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,2,5 and 9 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 65259-97: (7*6)+(6*5)+(5*2)+(4*5)+(3*9)+(2*9)+(1*7)=154 154 % 10 = 4 So 65259-97-4 is a valid CAS Registry Number.