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Double-struck capitals naming the standard number systems.
Also known as: Double-struck capitals, Blackboard bold, Number set symbols, Bold face number sets
Double-struck capitals name the number systems: N for the naturals, Z for the integers, Q for the rationals, R for the reals and C for the complex numbers. The letters come from German and Italian words rather than English, which is why Z stands for the integers and Q for the rationals.
Name the standard number systems: N the natural numbers, Z the integers, Q the rationals, R the reals, C the complex numbers.
Contexts: Mathematics
Take their letters from other languages — Z from Zahlen, German for numbers, and Q from quoziente, Italian for quotient — which is why they do not match the English names.
Contexts: Mathematics
Began as a blackboard imitation of bold type and became a typeface of its own, so printed texts may use either a double-struck or a plain bold capital.
Contexts: Mathematics
Disagree across texts on whether N includes zero, which is a convention each book must state rather than a settled fact.
Contexts: Mathematics
Capital letters drawn with one vertical stroke doubled, so each letter appears to have a hollow spine.