Australian Constitution - Section 24 - Constitution of House of Representatives
The House of Representatives shall be composed of members directly chosen by the people of the Commonwealth, and the number of such members shall be, as nearly as practicable, twice the number of senators.
The number of members chosen in the several States shall be in proportion to the respective members of their people, and shall, until the Parliament otherwise provides, be determined, whenever necessary, in the following manner:-
(i.) A quota shall be ascertained by dividing the number of the people of the Commonwealth, as shown by the latest statistics of the Commonwealth, by twice the number of senators:
(ii.) The number of members to be chosen in each State shall be determined by dividing the number of people of the State, as shown by the latest statistics of the Commonwealth, by the quota; and if on such division there is a remainder greater than one-half of the quota, one more member shall be chosen in the State.
But notwithstanding anything in this section, five members at least shall be chosen in each Original State.