The CAS Registry Mumber 60509-63-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,0,5,0 and 9 respectively; the second part has 2 digits, 6 and 3 respectively. Calculate Digit Verification of CAS Registry Number 60509-63: (7*6)+(6*0)+(5*5)+(4*0)+(3*9)+(2*6)+(1*3)=109 109 % 10 = 9 So 60509-63-9 is a valid CAS Registry Number.