The CAS Registry Mumber 80632-68-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,6,3 and 2 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 80632-68: (7*8)+(6*0)+(5*6)+(4*3)+(3*2)+(2*6)+(1*8)=124 124 % 10 = 4 So 80632-68-4 is a valid CAS Registry Number.