E. G. In a sports team where you're wearing numbers to show what position you're playing, or in a shop where you get a ticket telling you your number in the queue.
when would anyone encounter this sentence? i thought it would mean i'm 8 years old, but i guess it refers to physically being an eight
What the sentence suggested to me was a counter or office where one is assigned a number in the queue and wait for it to be called to get the service you want. In English, though, I would not include the definite article, but say "I am number eight."