The CAS Registry Mumber 6120-82-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 6,1,2 and 0 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 6120-82: (6*6)+(5*1)+(4*2)+(3*0)+(2*8)+(1*2)=67 67 % 10 = 7 So 6120-82-7 is a valid CAS Registry Number.