Digit of auspicious floor dust: 1, 6 belong to water, 2, 7 belong to fire, 3, 8 belong to wood, 4, 9 belong to gold, 5, 0 belong to earth.
First floor reachs 6 buildings to belong to north, belong to water
2 buildings reach 7 buildings to belong to south, belong to fire
3 buildings reach 8 buildings to belong to east, belong to wood
4 buildings reach 9 buildings to belong to the west, belong to gold
5 buildings reach 10 buildings to belong to in the center of, belong to earth
If be 15 buildings, so mantissa is 5, be informed above correspondence for earth, like earthy person, reach (autochthonal gold) the person that likes gold suits to live this floor.