It looks like your query "how long is 9" is a bit unclear. Could you please provide more context? For example:

• Are you asking about the length of the number 9 in digits?
• Are you referring to "9" as a measurement (like 9 inches, 9 feet, 9 meters)?
• Or is it related to something else, like time (9 hours) or a specific object named "9"?

With a bit more detail, I can give you a precise and helpful answer!