E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Sixes and Sevens (All).
Ill-assorted; not matched, higgledy-pig-gledy.
To be at sixes and sevens. Spoken of things, it means in confusion; spoken of persons, it means in disagreement or hostility Six, yea seven, was a Hebrew phrase meaning an indefinite number, hence we read in Job (v. 19), He [God] shall deliver thee in six troubles, yea in seven, etc. What is indefinite is confused. Our modern phrase would be five or six things here, and five or six things there, but nothing in proper order.
Old Odcombs odness makes not thee uneven,
Nor carelessly set all at six and seven.
Taylor: Workes, ii. 71 (1630).
Long and short sixes. Certain dip candles, common in the first half of the nineteenth century. Long sixes were those eight inches long, short sixes were thicker and about five inches long. Called sixes because six went to a pound.