The CAS Registry Mumber 80545-51-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,5,4 and 5 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 80545-51: (7*8)+(6*0)+(5*5)+(4*4)+(3*5)+(2*5)+(1*1)=123 123 % 10 = 3 So 80545-51-3 is a valid CAS Registry Number.