A special mathematical term that means "because".

/kloc-at the beginning of the 0/8th century, no one used ∵ to mean "because". It was not until 1805 that \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \ u \\ By 1827, Euclid's Elements of Geometry published by Cambridge University used ⊙ for "because" and ∴ for "so" respectively. This usage has become more and more popular and has been used ever since. ∫ [Because ]∴ [So], these two symbols are easily confused. Everyone should distinguish the difference between these two symbols!

The easiest way is to enter directly on the keyboard.

The method is (in any input method state), hold down the shift key (Alt key) with your left hand, and then press 4 1439 to release your left hand, and "∵" will come out.