The CAS Registry Mumber 67811-43-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,8,1 and 1 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 67811-43: (7*6)+(6*7)+(5*8)+(4*1)+(3*1)+(2*4)+(1*3)=142 142 % 10 = 2 So 67811-43-2 is a valid CAS Registry Number.