1. "∵" means: because.

2. "∴" means: so.

3. "∷" means: equal to, proportional to.

4. This is a math-specific term.

5. "∵" and "∴" were first used by the Swiss mathematician Johann Rahn, who used "∴" and "∵" as symbols in his 1659 book Teusche Algebra. He used the symbols "∴" and "∵" in his mathematical book "Teusche Algebra" published in 1659 to denote "so", of which "∴" was used more.

Expanded

Mathematical symbols:

1, perhaps China's ancient counting chips is one of the world's first symbols used in the origin of the Shang Dynasty divination.

2, most of the mathematical symbols we use today were not invented until after the 16th century, before that mathematics was written out in script, a deliberate procedure that would have limited its development.

3Today's symbols make math more accessible to people, but beginners are often intimidated by them. It is extremely compressed, with a small number of symbols containing a large number of messages, and, like musical notation, today's mathematical symbols have a clear syntax and encode messages that would be difficult to write in any other way.

Baidu Encyclopedia: Mathematics