House Numbers "Is your number up?"
From the National Fire Safety Council

Can we find you in an emergency?        
Clearly posted house numbers can save precious time should an emergency occur.  Response time is critical; seconds lost can mean the difference between life and death.  Approximately 84% of all fatal fires burn 10 or more minutes before the fire department is notified.     
       
Homes & Apartments - Post numbers:

• Directly on your house, apartment or garage.
• By the street or on a post or sign made of fire resistant material
• On the mailbox or curb
• Anywhere they can be easily seen from the road
• That are easy to read, not cursive style
• That are at least 4" high
• That can be seen at night
• That are visible from up to 150 feet at all angles
• Can be seen all year round