Sorry if this is not the right place to ask but I was suggested maybe trying here.
I live and work in Japan and today a co-worker and I were talking about math. Through our discussion we came across the question of why English count by thousands. I get base 10 and its origins but it's the naming we were wondering about. For example we have ones, tens, hundreds, and thousands. The next number instead of being a new name becomes ten thousands. The next "new" number is a million which is a thousand thousands. After that each new number comes at the thousand place. By comparison Japan got their number system form China and while also base 10 it counts by 10,000s. Why is this?
Weirdly the traditional English system means that a billion is a million million. So you have a new name once you have squared the base 10 system but its English so that rule gets broken as many times as its true. This I believe is due to English being mainly a mix of French and German based languages.
So 10,100,1000, 1,000,000. 1,000,000,000,000 Ten hundred thousand, million, billion
The American billion is more common which means a thousand million.
In short in English small numbers (up to 1000) come roughly from German and the larger numbers from French (million is French) (mille is French for 1000)(ten is zehn in German) (Norman conquest taking over a largely germanic/norse nation) Same reason beef is the meat - rich French Lords eat the meat. Cow is German (kuh) which the locals called the animal.
In short we count by thousands because the French (and later Europeans) do. The French metric system is the driving force behind the standardisation of units and counting systems.
You don't want to truly understand the nonsense that brits had in their traditional systems. We have largely adopted the European ways. You also don't want to learn about how the French count, 96? No 4 twenties and 16.
We all have mixed it up and come to a system that sort of works.