How To Write Avenue Number In Street Address With Apartment . Put a hyphen between the unit/suite/apartment number and the street number. When writing an address with an apartment number (i.e. How to Address Professional Letters Appropriately from preply.com Address line 1, then, can be seen as a kind of preview of the full address. Simply write or type the street number of your building or house, leave a space, and then finish off the line with your street name. Apt 920 13 prince of wales dr.