∫ means because, in the Handbook of Popular Mathematics published in Britain 1805, ∫ means because for the first time, but it didn't catch on. By 1827, Euclid's Elements of Geometry published by Cambridge University was represented by \ and ∴ respectively. Therefore, this usage has become more and more popular and has been used ever since.
Extended data:
The meaning of other mathematical symbols:
1, greater than or equal to greater than or equal to.
1, ≤≤≤
3. The ≡ constant is equal to or congruent.
4.π pi is about 3. 14 15926536 pi.