Draw your cutting line on the particle board, using a carpenter's square and yardstick to ensure that it is perfectly positioned and straight.
Set the blade depth on the table saw so that it only cuts through the lower 3/4 of the board's thickness.
Set the table saw's fence so that the pencil line is positioned in front of the blade.
Turn on the saw and push the board over the blade, scoring along the bottom side. Keep your fingers clear of the blade even though it does not pierce the top of the board.
Turn the board over and readjust the fence to line up the blade with the scored line. Cut the board again.
Cut the board again along the scored line, completely severing it into two pieces.