The CAS Registry Mumber 84866-43-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,8,6 and 6 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 84866-43: (7*8)+(6*4)+(5*8)+(4*6)+(3*6)+(2*4)+(1*3)=173 173 % 10 = 3 So 84866-43-3 is a valid CAS Registry Number.