+: Plus: add
−: Minus: subtract
×: Times: multiply
÷: Divided by: divide
=: Equals: is the same value as
≠: Is not equal to
<: Is less than
>: Is greater than
≤: Is less than or equal to
≥: Is greater than or equal to
≈: Is approximately equal to
≡: Is identical to or congruent (mod) to
±: Plus or minus
∓: Minus or plus
√: Square root (radical)
∛: Cube root
π: Pi: about 3.14159, circumference over diameter
∞: Infinity: unbounded, without end
%: Percent: out of 100
‰: Per mille: out of 1,000
°: Degree: a unit of angle or temperature
′: Prime: minutes, feet, or a related variable
″: Double prime: seconds, inches
|x|: Absolute value of x
!: Factorial
Σ: Sigma: sum of a series
Π (capital pi): Product of a series
Δ: Delta: change in
∂: Partial derivative
∫: Integral
∮: Contour or closed-loop integral
lim: Limit
θ: Theta: commonly an angle
λ: Lambda: wavelength, eigenvalue
μ: Mu: mean of a population
σ: Sigma (lowercase): standard deviation
ε (epsilon): A very small positive number in limits
φ: Phi: the golden ratio (about 1.618) or an angle
e: Euler's number, about 2.71828
i: Imaginary unit, where i² = −1
ℝ: The set of real numbers
ℚ: The set of rational numbers
ℤ: The set of integers
ℕ: The set of natural numbers
ℂ: The set of complex numbers
∈: Is an element of
∉: Is not an element of
⊂: Is a subset of
∪: Union: in either set
∩: Intersection: in both sets
∅: Empty set: no elements
∀: For all
∃: There exists
∴: Therefore
∵: Because
⇒: Implies
⇔: If and only if
∥: Is parallel to
⊥: Is perpendicular to
∠: Angle
△: Triangle
≅: Is congruent to
∼: Is similar to
∝: Is proportional to
f(x): Function f of x
f⁻¹: Inverse function of f
n!: n factorial: product of 1 to n
a:b: Ratio of a to b
⌊x⌋: Floor: greatest integer not above x
⌈x⌉: Ceiling: least integer not below x
mod: Modulo: the remainder after division
·: Dot: multiplication
→ (arrow): Approaches, or maps to

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