The CAS Registry Mumber 867-89-0 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 8,6 and 7 respectively; the second part has 2 digits, 8 and 9 respectively. Calculate Digit Verification of CAS Registry Number 867-89: (5*8)+(4*6)+(3*7)+(2*8)+(1*9)=110 110 % 10 = 0 So 867-89-0 is a valid CAS Registry Number.