# Math | Class XI | Set Theory | 02 | JEE Mains ADVANCED - Videos

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The number of distinct elements in a finite set is called its cardinal number. It is denoted as n(A) and read as ‘the number of elements of the set’. For example: (i) Set A = {2, 4, 5, 9, 15} has 5 elements.

Equal sets have the exact same elements in them, even though they could be out of order. Equivalent sets have different elements but have the same amount of elements.

In mathematics, a set A is a subset of a set B, or equivalently B is a superset of A, if A is “contained” inside B, that is, all elements of A are also elements of B. A and B may coincide. The relationship of one set being a subset of another is called inclusion or sometimes containment.

Proper subset definition. A proper subset of a set is a subset of that is not equal to . In other words, if is a proper subset of , then all elements of are in but contains at least one element that is not in . For example, if A = { 1 , 3 , 5 } then B = { 1 , 5 } is a proper subset of .

Power Set: The set of all the subsets of a set

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