What do you mean?
Yes I know, that but the point is that the resource POST /api/auctions/:page/:number with the body could be simply converted as query parameters this way:
/api/auctions/:page/:number ==> /api/auctions?page=1&resultsPerPage=1
Reason: the resource you are waintg to retrieve is "auctions", not the "number"
Also change "number" to "resultsPerPage", which is more clear as user. Can set a defalut number of "30" or just make it mandatory.
You can make "page" it mandatory giving a 4XX error and feedback.