The CAS Registry Mumber 86823-68-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,6,8,2 and 3 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 86823-68: (7*8)+(6*6)+(5*8)+(4*2)+(3*3)+(2*6)+(1*8)=169 169 % 10 = 9 So 86823-68-9 is a valid CAS Registry Number.