down cold, have

have (something) down cold

To learn, master, or understand something perfectly, to the point of requiring little or no focus to do, recall, or accomplish it. Make sure you practice these equations until you have them down cold. I always get my routine down cold so there won't be any room for error during the performance.
See also: cold, down, have

down cold, have

Learn or accomplish perfectly. For example, I have this song down cold. The slangy use of cold for "completely" dates from the late 1800s and the phrase itself from about 1900.
See also: down, have