Double-Struck Capital Q ℚ

U+211A
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Symbol Meaning

The set of rational numbers ℚ = {m/n} consists of numbers that can be expressed as ordinary fractions (for example, 4/3). In decimal representation, they can be finite or repeating decimals, such as 4/3 = 1.333... The term “rational” comes from the Latin word “quotient”, which furthermore developed in English. It's interesting enough that the set ℚ is also countable (equivalent in cardinality to the set of natural numbers ℕ).

The sets , , , , are often written in bold font (for example, in the works of Nicolas Bourbaki) or as double-struck letters on blackboards and manuscripts. The usage of double-struck font in printed texts was introduced by American mathematicians and became widespread with the famous textbook on complex analysis by Gunning and Rossi, published in 1965.

The symbol “Double-Struck Capital Q” is included in the “Letterlike symbols” subblock of the “Letterlike Symbols” block and was approved as part of Unicode version 1.1 in 1993.

Text is also available in the following languages: Español; Русский;

Synonyms

the set of rational numbers.

Unicode Name Double-Struck Capital Q
Unicode Number
HTML Code
CSS Code
Entity ℚ
Unicode Block Letterlike Symbols
Unicode Subblock Letterlike symbols
Unicode Version 1.1 (1993)
Version 1.1
Block Letterlike Symbols
Type of paired mirror bracket (bidi) None
Composition Exclusion No
Case change 211A
Simple case change 211A
Math +
Alphabetic +
Uppercase +
Cased +
ID_Start +
ID_Continue +
XID_Start +
XID_Continue +
Grapheme_Base +
age 1.1
scripts Common
Encoding hex dec (bytes) dec binary
UTF-8 E2 84 9A 226 132 154 14845082 11100010 10000100 10011010
UTF-16BE 21 1A 33 26 8474 00100001 00011010
UTF-16LE 1A 21 26 33 6689 00011010 00100001
UTF-32BE 00 00 21 1A 0 0 33 26 8474 00000000 00000000 00100001 00011010
UTF-32LE 1A 21 00 00 26 33 0 0 438370304 00011010 00100001 00000000 00000000

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