The CAS Registry Mumber 902-82-9 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 9,0 and 2 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 902-82: (5*9)+(4*0)+(3*2)+(2*8)+(1*2)=69 69 % 10 = 9 So 902-82-9 is a valid CAS Registry Number.