The CAS Registry Mumber 82203-02-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,2,0 and 3 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 82203-02: (7*8)+(6*2)+(5*2)+(4*0)+(3*3)+(2*0)+(1*2)=89 89 % 10 = 9 So 82203-02-9 is a valid CAS Registry Number.