Should an election of representatives in Congress occur after the number of representatives to which the state is entitled changes, and before the districts have changed to conform to the new apportionment, representatives shall be chosen as follows: If the number of representatives is increased, then one (1) member shall be chosen in each district as organized, and the additional member or members shall be chosen by the electors of the state at large; and if the number of representatives is decreased, then the whole number shall be chosen by the electors of the state at large.