# Math Symbols

**Topics:**Normal distribution, Probability theory, Random variable

**Pages:**11 (2576 words)

**Published:**March 11, 2013

≠| not equal sign| inequality| 5 ≠ 4|

>| strict inequality| greater than| 5 > 4|

<| strict inequality| less than| 4 < 5|

≥| inequality| greater than or equal to| 5 ≥ 4|

≤| inequality| less than or equal to| 4 ≤ 5|

( )| parentheses| calculate expression inside first| 2 × (3+5) = 16| [ ]| brackets| calculate expression inside first| [(1+2)*(1+5)] = 18| +| plus sign| addition| 1 + 1 = 2|

−| minus sign| subtraction| 2 − 1 = 1|

±| plus - minus| both plus and minus operations| 3 ± 5 = 8 and -2| ∓| minus - plus| both minus and plus operations| 3 ∓ 5 = -2 and 8| *| asterisk| multiplication| 2 * 3 = 6|

×| times sign| multiplication| 2 × 3 = 6|

∙ | multiplication dot| multiplication| 2 ∙ 3 = 6| ÷| division sign / obelus| division| 6 ÷ 2 = 3|

/| division slash| division| 6 / 2 = 3|

–| horizontal line| division / fraction| |

mod| modulo| remainder calculation| 7 mod 2 = 1|

.| period| decimal point, decimal separator| 2.56 = 2+56/100| a b| power| exponent| 23 = 8|

a^b| caret| exponent| 2 ^ 3 = 8|

√a| square root| √a · √a = a| √9 = ±3|

3√a| cube root| | 3√8 = 2|

4√a| forth root| | 4√16 = ±2|

n√a| n-th root (radical)| | for n=3, n√8 = 2|

%| percent| 1% = 1/100| 10% × 30 = 3|

‰| per-mille| 1‰ = 1/1000 = 0.1%| 10‰ × 30 = 0.3| ppm| per-million| 1ppm = 1/1000000| 10ppm × 30 = 0.0003| ppb| per-billion| 1ppb = 1/1000000000| 10ppb × 30 = 3×10-7| ppt| per-trillion| 1ppb = 10-12| 10ppb × 30 = 3×10-10| Geometry symbols Symbol| Symbol Name| Meaning / definition| Example| ∠| angle| formed by two rays| ∠ABC = 30º|

∡| measured angle| | ∡ABC = 30º|

∢| spherical angle| | ∢AOB = 30º|

∟| right angle| = 90º| α = 90º|

º| degree| 1 turn = 360º| α = 60º|

´| arcminute| 1º = 60´| α = 60º59'|

´´| arcsecond| 1´ = 60´´| α = 60º59'59''|

| line| infinite line| |

AB| line segment| line from point A to point B| |

| ray| line that start from point A| |

| arc| arc from point A to point B| |

|| perpendicular| perpendicular lines (90ºangle)| AC |BC| ||| parallel| parallel lines| AB || CD|

≅| congruent to| equivalence of geometric shapes and size| ∆ABC ≅ ∆XYZ| ~| similarity| same shapes, not same size| ∆ABC ~ ∆XYZ| Δ| triangle| triangle shape| ΔABC ≅ ΔBCD|

| x-y || distance| distance between points x and y| | x-y | = 5| π| pi constant| π = 3.141592654...is the ratio between the circumference and diameter of a circle| c = π·d = 2·π·r| rad| radians| radians angle unit| 360º = 2π rad|

grad| grads| grads angle unit| 360º = 400 grad|

Algebra symbols 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| f(x) ∝ g(x)| ∞| 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...

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