A set of two numbers or objects linked in some way is said to be a pair. The pair 
and 
is usually denoted (
, 
),
and is generally considered to be ordered, making it a 2-tuple.
In certain circumstances, pairs are also called brothers
or twins.
Pair
See also
Amicable Pair, Augmented Amicable Pair, Brothers, Brown Numbers, Friendly Pair, Hexad, Homogeneous Numbers, Impulse Pair, Irregular Pair, Lax Pair, Long Exact Sequence of a Pair Axiom, Monad, n-Tuple, Ordered Pair, Pairwise, Perko Pair, Quadruple, Quasiamicable Pair, Quintuplet, Smith Brothers, Triad, Triple, Twin Peaks, Twin Primes, Twins, Unitary Amicable Pair, Wilf-Zeilberger Pair, Zip-PairExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Pair." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Pair.html