Home U+2100 to U+214F Letterlike Symbols

# U+211A DOUBLE-STRUCK CAPITAL Q

U+211A was added to Unicode in version 1.1 (1993). It belongs to the block U+2100 to U+214F Letterlike Symbols in the U+0000 to U+FFFF Basic Multilingual Plane.

This character is a Uppercase Letter and is commonly used, that is, in no specific script. The character is also known as the set of rational numbers.

The glyph is a Font composition of the glyph Latin Capital Letter Q. It has a Neutral East Asian Width. In bidirectional context it acts as Left To Right and is not mirrored. The glyph can, under circumstances, be confused with 1 other glyphs. In text U+211A behaves as Alphabetic regarding line breaks. It has type Upper for sentence and Alphabetic Letter for word breaks. The Grapheme Cluster Break is Any.

In mathematics, a rational number is a number that can be expressed as the quotient or fraction p/q of two integers, a numerator p and a non-zero denominator q. For example, −3/7 is a rational number, as is every integer (e.g. 5 = 5/1). The set of all rational numbers, also referred to as "the rationals", the field of rationals or the field of rational numbers is usually denoted by boldface Q, or blackboard bold Q . {displaystyle mathbb {Q} .}

A rational number is a real number. The real numbers that are rational are those whose decimal expansion either terminates after a finite number of digits (example: 3/4 = 0.75), or eventually begins to repeat the same finite sequence of digits over and over (example: 9/44 = 0.20454545...). This statement is true not only in base 10, but also in every other integer base, such as the binary and hexadecimal ones (see Repeating decimal § Extension to other bases).

A real number that is not rational is called irrational. Irrational numbers include √2, π, e, and φ. Since the set of rational numbers is countable, and the set of real numbers is uncountable, almost all real numbers are irrational.

Rational numbers can be formally defined as equivalence classes of pairs of integers (p, q) with q ≠ 0, using the equivalence relation defined as follows:

( p 1 , q 1 ) ∼ ( p 2 , q 2 ) ⟺ p 1 q 2 = p 2 q 1 . {displaystyle left(p_{1},q_{1} ight)sim left(p_{2},q_{2} ight)iff p_{1}q_{2}=p_{2}q_{1}.}

The fraction p/q then denotes the equivalence class of (p, q).

Rational numbers together with addition and multiplication form a field which contains the integers, and is contained in any field containing the integers. In other words, the field of rational numbers is a prime field, and a field has characteristic zero if and only if it contains the rational numbers as a subfield. Finite extensions of Q are called algebraic number fields, and the algebraic closure of Q is the field of algebraic numbers.

In mathematical analysis, the rational numbers form a dense subset of the real numbers. The real numbers can be constructed from the rational numbers by completion, using Cauchy sequences, Dedekind cuts, or infinite decimals (see Construction of the real numbers).

## Representations

System Representation
8474
UTF-8 E2 84 9A
UTF-16 21 1A
UTF-32 00 00 21 1A
URL-Quoted %E2%84%9A
HTML-Escape &#x211A;
Wrong windows-1252 Mojibake â
HTML-Escape &Qopf;
HTML-Escape &rationals;
alias the set of rational numbers
LATEX \mathbb{Q}

## Complete Record

Property Value
Age 1.1 (1993)
Unicode Name DOUBLE-STRUCK CAPITAL Q
Unicode 1 Name DOUBLE-STRUCK Q
Block Letterlike Symbols
General Category Uppercase Letter
Script Common
Bidirectional Category Left To Right
Combining Class Not Reordered
Decomposition Type Font
Decomposition Mapping Latin Capital Letter Q
Lowercase
Simple Lowercase Mapping Double-Struck Capital Q
Lowercase Mapping Double-Struck Capital Q
Uppercase
Simple Uppercase Mapping Double-Struck Capital Q
Uppercase Mapping Double-Struck Capital Q
Simple Titlecase Mapping Double-Struck Capital Q
Titlecase Mapping Double-Struck Capital Q
Case Folding Double-Struck Capital Q
ASCII Hex Digit
Alphabetic
Bidi Control
Bidi Mirrored
Composition Exclusion
Case Ignorable
Changes When Casefolded
Changes When Casemapped
Changes When NFKC Casefolded
Changes When Lowercased
Changes When Titlecased
Changes When Uppercased
Cased
Full Composition Exclusion
Default Ignorable Code Point
Dash
Deprecated
Diacritic
Emoji Modifier Base
Emoji Component
Emoji Modifier
Emoji Presentation
Emoji
Extender
Extended Pictographic
FC NFKC Closure Latin Small Letter Q
Grapheme Cluster Break Any
Grapheme Base
Grapheme Extend
Hex Digit
Hyphen
ID Continue
ID Start
IDS Binary Operator
IDS Trinary Operator and
Ideographic
Indic Mantra Category
Indic Positional Category NA
Indic Syllabic Category Other
Jamo Short Name
Join Control
Logical Order Exception
Math
Noncharacter Code Point
NFC Quick Check Yes
NFD Quick Check Yes
NFKC Casefold Latin Small Letter Q
NFKC Quick Check No
NFKD Quick Check No
Other Alphabetic
Other Default Ignorable Code Point
Other Grapheme Extend
Other ID Continue
Other ID Start
Other Lowercase
Other Math
Other Uppercase
Prepended Concatenation Mark
Pattern Syntax
Pattern White Space
Quotation Mark
Regional Indicator
Sentence Break Upper
Soft Dotted
Sentence Terminal
Terminal Punctuation
Unified Ideograph
Variation Selector
Word Break Alphabetic Letter
White Space
XID Continue
XID Start
Expands On NFC
Expands On NFD
Expands On NFKC
Expands On NFKD
Bidi Paired Bracket Double-Struck Capital Q
Bidi Paired Bracket Type None
East Asian Width Neutral
Hangul Syllable Type Not Applicable
ISO 10646 Comment
Joining Group No_Joining_Group
Joining Type Non Joining
Line Break Alphabetic
Numeric Type None
Numeric Value not a number
Simple Case Folding Double-Struck Capital Q
Script Extension
Vertical Orientation R