In set theory, an ordinal number, or ordinal, is a generalization of ordinal numerals (first, second, n th, etc.) aimed to extend enumeration to infinite sets. [1] A finite set can be enumerated by successively labeling each element with the least natural number that has not been previously used.:max_bytes(150000):strip_icc()/close-up-of-number-5-candle-on-birthday-cake-594189533-5c3c22f0c9e77c0001275b63.jpg)
Ordinal numbers show position or order, like first, second, and third. Ordinal numbers end with -nd, -rd, -st, or -th, such as 2nd, 3rd, and 1st. When using ordinal and cardinal numbers together, ordinals go before cardinals like first two.