The CAS Registry Mumber 5009-82-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,0,0 and 9 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 5009-82: (6*5)+(5*0)+(4*0)+(3*9)+(2*8)+(1*2)=75 75 % 10 = 5 So 5009-82-5 is a valid CAS Registry Number.