SymbolSymbol NameMeaning / definitionExample
xx variableunknown value to findwhen 2x = 4, then x = 2
equivalenceidentical to 
equal by definitionequal by definition 
:=equal by definitionequal by definition 
~approximately equalweak approximation11 ~ 10
approximately equalapproximationsin(0.01) ≈ 0.01
proportional toproportional toy ∝ x when y = kx, k constant
lemniscateinfinity symbol 
much less thanmuch less than1 ≪ 1000000
much greater thanmuch greater than1000000 ≫ 1
( )parenthesescalculate expression inside first2 * (3+5) = 16
[ ]bracketscalculate expression inside first[(1+2)*(1+5)] = 18
{ }bracesSet 
xfloor bracketsrounds number to lower integer⌊4.3⌋ = 4
xceiling bracketsrounds number to upper integer⌈4.3⌉ = 5
x!exclamation markfactorial4! = 1*2*3*4 = 24
x |single vertical barabsolute value| -5 | = 5
f (x)function of xmaps values of x to f(x)f (x) = 3x+5
(f ∘ g)function composition(f ∘ g) (x) = f (g(x))f (x)=3x,g(x)=x-1 ⇒(f ∘ g)(x)=3(x-1)
(a,b)open interval(a,b) = {x | a < x < b}x∈ (2,6)
[a,b]closed interval[a,b] = {x | a ≤ x ≤ b}x ∈ [2,6]
deltachange / differencet = t1  t0
discriminantΔ = b2 – 4ac 
sigmasummation – sum of all values in range of series xi= x1+x2+…+xn
∑∑sigmadouble summation
capital piproduct – product of all values in range of series xi=x1∙x2∙…∙xn
ee constant / Euler’s numbere = 2.718281828…e = lim (1+1/x)x , x→∞
γEuler-Mascheroni  constantγ = 0.527721566… 
φgolden ratiogolden ratio constant 
πpi constantπ = 3.141592654…

is the ratio between the circumference and diameter of a circle

 

c = π·d = 2·π·r