The CAS Registry Mumber 83268-54-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,2,6 and 8 respectively; the second part has 2 digits, 5 and 4 respectively. Calculate Digit Verification of CAS Registry Number 83268-54: (7*8)+(6*3)+(5*2)+(4*6)+(3*8)+(2*5)+(1*4)=146 146 % 10 = 6 So 83268-54-6 is a valid CAS Registry Number.