1 Geometric symbol ⊥∥∠⌒⊙≌△ 2 Algebraic symbol ∧∧∧∨ ~ ∫≦≤∞: 3 Operational symbol × ⊙. π (pi) 6 inference symbol | a | ⊥∽△∠∩∪≠≡≥≤∈↓→↓ ↖↗↘↙↙↙. ① ② ③ ④ ⑤ ⑧ ⑨ ⑩ δ θ ξ π σ ψ ξ α β γ δ ε ζ θ ι λ μ ν ξ ο π υ σ ψ υ υ φ ψ ψ Ⅰ Ⅱ Ⅲ?ⅷ ⅸ Minus sign plus sign or minus sign minus sign × multiplied sign ÷ divided sign = equal number ≠ unequal number ≡ equal to all equal numbers ≠ yes. About equal to about ≈ about equal to about equal to number greater than number less than or equal to less than or equal to greater than or equal to. Thanks or equal to greater than or equal to% percentage …∞ infinity infinity infinity √ (square) square root x square x cube x cube √; Because ∴ hence ∠ angle ⌒ semicircle ⊙ circle χ circumference △ triangle triangle ⊥ perpendicular to the union of ∪ intersection, the union of set ∩ intersection, the total integration of integral ∫ (σ)' minutes ∫ seconds #.