Choose a port (A,B, or C). Connect the low 4 pins of the port to carry the number you want to display and connect those to the data pins of the CD4543BE. Then connect the 4 pins of the high byte to the latches. to write "2" to the first digit, send "12" to the port. to write 9 to the second digit send "29" to the port. Write 6 to the 3rd port with "46" and so on.