Linked from
The 69 pages that link to Rational number, each with the reason it gives.
Equivalence relationRelated: Rational numbers can be constructed from equivalent pairs of integers.
CardinalityRelated: They are dense on the number line yet still countable.
Positional notationRelated: Finite or repeating positional expansions represent rational numbers.
Total orderRelated: The usual numerical order compares every pair of rational numbers.
Cardinal numberRelated: Despite lying densely on the number line, the rationals are countable.
OneRelated: One is rational and has many equivalent fractional representations.
ReciprocalRelated: The reciprocal of a nonzero rational number is rational.
Archimedean propertyRelated: The rationals satisfy the property despite lacking completeness.
Nth rootRelated: A rational radicand can have an irrational root, as with the square root of two.