The CAS Registry Mumber 84066-40-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,0,6 and 6 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 84066-40: (7*8)+(6*4)+(5*0)+(4*6)+(3*6)+(2*4)+(1*0)=130 130 % 10 = 0 So 84066-40-0 is a valid CAS Registry Number.