Symbol  Symbol Name  Meaning / definition  Example 
x  x variable  unknown value to find  when 2x = 4, then x = 2 
≡  equivalence  identical to  
≜  equal by definition  equal by definition  
:=  equal by definition  equal by definition  
~  approximately equal  weak approximation  11 ~ 10 
≈  approximately equal  approximation  sin(0.01) ≈ 0.01 
∝  proportional to  proportional to  y ∝ x when y = kx, k constant 
∞  lemniscate  infinity symbol  
≪  much less than  much less than  1 ≪ 1000000 
≫  much greater than  much greater than  1000000 ≫ 1 
( )  parentheses  calculate expression inside first  2 * (3+5) = 16 
[ ]  brackets  calculate expression inside first  [(1+2)*(1+5)] = 18 
{ }  braces  Set  
⌊x⌋  floor brackets  rounds number to lower integer  ⌊4.3⌋ = 4 
⌈x⌉  ceiling brackets  rounds number to upper integer  ⌈4.3⌉ = 5 
x!  exclamation mark  factorial  4! = 1*2*3*4 = 24 
 x   single vertical bar  absolute value   5  = 5 
f (x)  function of x  maps 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)=x1 ⇒(f ∘ g)(x)=3(x1) 
(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] 
∆  delta  change / difference  ∆t = t_{1}_{ }– t_{0} 
∆  discriminant  Δ = b^{2} – 4ac  
∑  sigma  summation – sum of all values in range of series  ∑ x_{i}= x_{1}+x_{2}+…+x_{n} 
∑∑  sigma  double summation  
∏  capital pi  product – product of all values in range of series  ∏ x_{i}=x_{1}∙x_{2}∙…∙x_{n} 
e  e constant / Euler’s number  e = 2.718281828…  e = lim (1+1/x)^{x} , x→∞ 
γ  EulerMascheroni constant  γ = 0.527721566…  
φ  golden ratio  golden ratio constant  
π  pi constant  π = 3.141592654…
is the ratio between the circumference and diameter of a circle

c = π·d = 2·π·r 
Emmanuel Abara Benson
I'm a highlyevolved 21st century human, a lover of knowledge and a Creative Writer amongst other things...
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