why does chinese have two number systems?

[rich kite]

just learned that chinese uses two different character sets for numbers like one is 一 but in the other set it is 壹 why is that?

[jovial apex]

one for dollar notes if i remember right

The other for daily use

[rich kite]

so their isn't any other use outside the financial sector

like is it used for documents and lawsuits and any official papers

and why the need to have two ways to write each character

[jovial apex]

There is sometimes used for money counting and some chinese calenswe

Caldender*

甘一< for example

[rich kite]

what is 甘一

[jovial apex]

廿一”

Wrong word

Used to represent 21

廿nian for 20

卅sa for 30

[rich kite]

oh so these are the special number characters for 30 and 20?

yeah thanks but i still don't know why they even have them.

[jovial apex]

For 40

[gleaming valve]

Usually 壹 for checks or bank-related documents. They can prevent it from being modified.

https://baike.baidu.hk/item/壹/37883

[jovial apex]

:3