If a voter casts only one preference, he gives his favourite just 1 point.

If another casts two preferences, she gives her favourite 2 points, and her 2nd choice 1 point.

If yet another casts three preferences, he gives his favourite 3 points, his 2nd choice 2 and his 3rd choice 1 point.

So best of all.

She who casts all five preferences gives her favourite 5 points, her 2nd choice 4, and so on.