A cardinal number is a number used to denote the size or quantity of a set, typically representing a counting number such as 1, 2, 3, and so on. These numbers are used for counting and ordering elements within a set. Unlike ordinal numbers, which indicate the position or order of an item in a sequence (such as first, second, third), cardinal numbers specifically convey the quantity or size of a group.
For example, in the sequence 3, 8, 12, 5, 20, the cardinal numbers are 3, 8, 12, 5, and 20, representing the count or quantity of items in the sequence. Cardinal numbers are fundamental in mathematics and have various applications in counting, measuring, and describing the size of sets or collections.