English also has words like dozen (12) and score (20).
I guess it came from the physical counting in trading. Imagine counting 96 small items. It makes sense to group them into scores and then count the scores. 1 score 2 score 3 score 4 score and a half score. Then there are few remaining that didn’t fit it neatly in scores and then counted last. That’s a total of 1, 2, 3, 4, 5, 6 plus the 4 and a half scores.
Easy. We often use idioms for comparisons.
One old way would be: “Trump and Hitler are both 2/3 yards from one piece” which means “They’re cut from the same (bad) fabric”.
Fabric was cut in an old measurement"alen" which was 2 foot or 2/3 yards, so simply stating the length would be understood as fabric, similar to how everyone knows that a 2x4s is a piece of wood and such.