The CAS Registry Mumber 80104-45-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,1,0 and 4 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 80104-45: (7*8)+(6*0)+(5*1)+(4*0)+(3*4)+(2*4)+(1*5)=86 86 % 10 = 6 So 80104-45-6 is a valid CAS Registry Number.