The CAS Registry Mumber 80027-68-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,0,2 and 7 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 80027-68: (7*8)+(6*0)+(5*0)+(4*2)+(3*7)+(2*6)+(1*8)=105 105 % 10 = 5 So 80027-68-5 is a valid CAS Registry Number.