Apartment building address numbers (order of placement)?

Question:I'm replacing the street address numbers on my two unit apartment building. Physically, apartment #102 is the top level unit and #100 is the lower unit. These are actual street numbers. When I place the numbers on the building, by the main door, should 102 be on top of 100? Or should 100 be on top of 102? More curious about stylistic principles than anything, since my house numbers were so #$#& expensive. Thanks!

Answers:
Yes 102 should be on top. I'm a mailman, I know these type of things...hehehe ;)