If the polls are right, Donald Trump will win South Carolina on Saturday by a double-digit margin.

That could earn him 100 percent of the state’s delegates.

That’s because the state awards its delegates on a winner-take-all basis by congressional district and statewide. So if Mr. Trump wins every congressional district and the statewide vote, he will win all of the state’s 50 delegates.

The possibility that South Carolina could award all or nearly all of its delegates to a single candidate is an extreme example of how the G.O.P. delegate rules work, but it makes it easy to imagine how a candidate like Donald Trump could win a majority of delegates without anything near a majority of the popular vote.

He could win with less than 40 percent of the vote in a true three-way race. He could win with even less the longer the field is split.