Mathematical symbols, such as plus sign (+), minus sign (-), multiplication sign (× or? ), division sign (÷ or/), union (∩), intersection (∩), radical sign (∩), logarithm (log, lg, ln), ratio (:), differential (dx), integral (∩) of two sets. ) and so on. Relational symbols such as "=" are equal signs, "≈" are approximate signs, "≦" are unequal signs and ">" is greater than sign. "

F:X→Y f is the greatest common divisor LCM (x, y) x and the least common multiple c complex set n of the function gcd (x, y) x from x to y.

Natural number set: N* Positive natural number set P Prime Set Q Rational Number Set R Real Number Set Z Integer Set Meaning Symbol Meaning = equal to ≠ not equal to greater than || Parallel is parallel to? Is greater than or equal to greater than or equal to? Less than or equal to less than or equal to ≡ Constant is equal to or completely equal to ππππ| X | X's absolute value ∽ Similar is equal to ≌ congruence is equal to (especially for triangles) >> is much greater than the sign.