Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_11336756_6 (length VARCHAR, remarks VARCHAR)
### Question:
What unit of length is being used for the route with "replaced by us 81" in their remarks section?
### Answer:
SELECT length FROM table_11336756_6 WHERE remarks = "Replaced by US 81"