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Combinatorics is not necessarily tangible, so the question of what it means to physically rearrange objects is irrelevant. On the other hand, it's easy to write down the permutations of small finite numbers of objects:

    0: []
    1: [1]
    2: [1,2] [2,1]
    3: [1,2,3] [1,3,2] [2,1,3] [2,3,1] [3,1,2] [3,2,1]