The CAS Registry Mumber 84681-43-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,6,8 and 1 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 84681-43: (7*8)+(6*4)+(5*6)+(4*8)+(3*1)+(2*4)+(1*3)=156 156 % 10 = 6 So 84681-43-6 is a valid CAS Registry Number.