一藏之數 The Weight of a Whole Canon
大王子見了，叫道：「兄弟，莫費力了。師父的兵器，俱是神兵，不知有多少重哩。」八戒笑道：「我的鈀也沒多重，只有一藏之數，連柄五千零四十八斤。」大王子见了，叫道：「兄弟，莫费力了。师父的兵器，俱是神兵，不知有多少重哩。」八戒笑道：「我的钯也没多重，只有一藏之数，连柄五千零四十八斤。」
逐句解 Line by line
The eldest prince saw it and called out, "Brothers, do not waste your strength.
He has been here before, in the courtyard with the rod, and he recognises it at once. 莫費力, do not spend effort, is an older brother saving two younger ones from a humiliation he has already had.
The masters' weapons are all divine arms. There is no telling how much they weigh."
神兵, divine weapons, is the phrase the chapter has used since the poem over the courtyard and will use again at the very end. 哩 is a light closing flourish giving the line a spoken lift, the way an ordinary person trails off.
Bajie laughed and said, "My rake is not so very heavy. It comes to the tally of one canon — five thousand and forty-eight catties, handle included."
Bajie says his rake is not heavy and then names a number that is one of the best jokes in the novel. 一藏之數, the tally of one 藏, counts the scrolls in a complete Buddhist canon — five thousand and forty-eight — and 藏 is zàng here, the canon, the same character and reading that stands in Tripitaka's own name. So the rake weighs exactly one set of the scriptures the whole pilgrimage is walking west to fetch. And a pig reports it, as a modest quantity, with the handle thrown in.
Five thousand and forty-eight is not a round number and it is not arbitrary. It is the count of scrolls in the canon, and Tripitaka's name in Chinese means precisely that canon.
So the joke is that Bajie is carrying the scriptures already, in the form of a farm tool, and has been for the whole journey. The novel does not point this out. It puts the number in his mouth in a throwaway boast about how light his rake is.
It is worth adding that the number's exactness is what makes it work. Had the text said five thousand, nothing would happen. The forty-eight is what tells a Chinese reader which five thousand this is.