Because it is: it is ∴. The invention and use of mathematical symbols are later than numbers, but their number exceeds numbers. There are more than 200 mathematical symbols commonly used in modern mathematics, and each symbol has an interesting experience. For example, "=" is an equal sign, ""is an approximate symbol (that is, approximately equal to), and "≦" is an unequal sign.

Because the source of symbolic expression

Ryan was the first person to express "so" with symbols. In an algebra book 1659, he used symbols ∴ and \ to mean "so", of which ∴ was used more. The English version of the book 1668 also uses these two symbols to mean "so", but "∵" is used more. Jones uses ∴ in 1706 to mean "so". By the middle of18th century, "∵" was used to mean "so", at least as much as "∴". "

/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.