At Sixes and Sevens
The expression "at sixes and sevens" means "in a state of disorder or confusion; topsy-turvy." For example, my math class is often at sixes and sevens!
Supposedly, the expression is very old, being traced back to Chaucer's use of it in Troylus and Cryserde in 1375. Others claim it is much older.
One author claims it is from Job 5:19, which reads "He shall deliver thee in six troubles: yea, in seven there shall no evil touch thee."
Another author traces it directly to the Arabic numerals 6 and 7. That is, they supposedly extend higher and lower respectively in a multi-digit number, making them irregular.
And a third author claims it is from an old two-dice game called Hazard (akin to craps), where the stated intent to roll a sum of 5 or 6 was considered maximally risky...i.e. was "reckless in the extreme." But, when you study the game itself, this claim is not true.
Sorry, can't write any more presently, as my mind is at sixes and sevens!