An apprentice witch will work for a year and a day, that is, a total of 366 days. Young Rowena gets such a job, and it is paid a daily wage that is some small sum, less than one galleon per day, in addition to room and board.
At the end of the apprenticeship, Rowena takes all the coins to the Gringotts bank and gets told she now has a pile of galleons, 11 sickles, and 11 knuts.
How big is the pile of galleons?
(17 sickles make one galleon, and 29 knuts make one sickle)