List of mathematical symbols
The list below has some of the most common symbols in mathematics. However, these symbols can have other meanings in different contexts other than math.
Name | Read as | Description | Meaning | Example(s) |
---|---|---|---|---|
= |
equality | equals, is equal to | If x=y, x and y represent the same value or thing. | 2+3=5 |
≡ |
definition | is defined as | If x≡y, x is defined as another name of y | (a+b)2≡a2+2ab+b2 |
≈ |
approximately equal | is approximately equal to | If x≈y, x and y are almost equal. | √2≈1.41 |
≠ |
inequation | does not equal, is not equal to | If x≠y, x and y do not represent the same value or thing. | 1+1≠3 |
< |
strict inequality |
is less than | If x<y, x is less than y. | 4<5 |
> |
is greater than | If x>y, x is greater than y. | 3>2 | |
≪ |
is much less than | If x≪y, x is much less than y. | 1≪999999999 | |
≫ |
is much greater than | If x≫y, x is much greater than y. | 999999999≫0.001 | |
≤ |
inequality |
is less than or equal to | If x≤y, x is less than or equal to y. | 5≤6 and 5≤5 |
≥ |
is greater than or equal to | If x≥y, x is greater than or equal to y. | 2≥1 and 2≥2 | |
∝ |
proportionality | is proportional to | If x∝y, then y=kx for some constant k. | If y=4x then y∝x and x∝y |
+ |
addition | plus | x+y is the sum of x and y. | 2+3=5 |
- |
subtraction | minus | x-y is the subtraction of y from x | 5-3=2 |
× |
multiplication | times | x×y is the multiplication of x by y | 4×5=20 |
· |
x·y is the multiplication of x by y | 4·5=20 | ||
÷ |
division | divided by | x÷y or x/y is the division of x by y | 20÷4=5 and 20/4=5 |
/ |
20/4=5 | |||
± |
plus-minus | plus or minus | x±y means both x+y and x-y | The equation 3±√9 has two solutions, 0 and 6. |
∓ |
minus-plus | minus or plus | 4±(3∓5) means both 4+(3-5) and 4-(3+5) | 6∓(1±3)=2 or 4 |
√ |
square root | square root | √x is a nonnegative number whose square is x. | √4=2 |
∑ |
summation | sum over … from … to … of, sigma | is the same as x1+x2+x3+...+xn | |
∏ |
multiplication | product over … from … to … of | is the same as x1×x2×x3×....×xn | =1×2×3×4×5=120 |
! |
factorial | factorial | n! is the product 1×2×3...×n | 5!=1×2×3×4×5=120 |
⇒ |
material implication | implies | A⇒B means that if A is true, B must also be true, but if A is false, B is unknown. | x=3⇒x2=9, but x2=9⇒x=3 is false, because x could also be -3. |
⇔ |
material equivalence | if and only if | If A is true, B is true and if A is false, B is false. | x=y+1⇔x-1=y |
|…| |
absolute value | absolute value of | |x| is the distance along the real line (or across the complex plane) between x and zero | |5|=5 and |-5|=5 |
|| |
parallel | is parallel to | If A||B then A and B are parallel | |
⊥ |
perpendicular | is perpendicular to | If A⊥B then A is perpendicular to B | |
≅ |
congruence | is congruent to | If A≅B then shape A is congruent to shape B (has the same measurements) | |
φ |
golden ratio | golden ratio | The golden ratio is an irrational number equal to (1+√5)÷2 or approximately 1.6180339887. | |
∞ |
infinity | infinity | ∞ is a symbol used to represent unending amounts. | |
∈ |
set membership | is an element of | a∈S means that a is an element of the set S | 3.5∈ℝ, 1∈ℕ, 1+i∈ℂ |
∉ |
is not an element of | a∉S means that a is not an element of the set S | 2.1∉ℕ, 1+i∉ℝ | |
{,} |
Set brackets | the set of | {a,b,c} is the set consisting of a, b, and c | ℕ={0,1,2,3,4,5...} |
ℕ |
Natural numbers | N | ℕ denotes the set of natural numbers {0,1,2,3,4,5...} (0 may or may not be included as natural number) | |
ℤ |
Integers | Z | ℤ denotes the set of integers (-3,-2,-1,0,1,2,3...) | |
ℚ |
Rational numbers | Q | ℚ denotes the set of rational numbers (numbers that can be written as a fraction a/b where a∈ℤ, b∈ℕ) | 8.323∈ℚ, 7∈ℚ, π∉ℚ |
ℝ |
Real numbers | R | ℝ denotes the set of real numbers | π∈ℝ, 7∈ℝ, √(-1)∉ℝ |
ℂ |
Complex numbers | C | ℂ denotes the set of complex numbers | √(-1)∈ℂ |
x̄ |
Mean | bar, overbar | x̄ is the mean (average) of xi | if x={1,2,3} then x̄=2 |
x̄ |
complex conjugate | the complex conjugate of x | If x=a + bi, then x̄=a - bi where i=√(-1) | x=-4 + 5.3i, x̄=-4 - 5.3i |
[+|-] | situational plus minus | Either plus or minus depending on the situation. | If y=[+|-]x then x is either positive or negative depending on the situation. | y=[+|-]x y equals either +x or -x depending on the scenario. |
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