How much of a $5 bill can be missing?

Can you please elaborate on the specific situation you're asking about with the "$5 bill"? Are you wondering about the physical integrity of the bill itself, or are you asking about the monetary value that can be missing before it's considered invalid? In general, for a $5 bill to remain legal tender, it must retain its essential identifying features, such as the serial number, portrait, and denomination, among others. Minor tears or creases generally don't affect its validity, but if a significant portion of the bill is missing, it may no longer be accepted as legal tender.