An elementary fact about permutations of a finite number of objects is that each one has a finite order. The order of a permutation is the smallest number of times it needs to be applied to bring all of the objects back into their original arrangement. The order of (ABCD) is 4: (ABCD)2 = (AC)(BD), (ABCD)3 = (ADCB), and finally, (ABCD )4 = ( ). It should be clear that the order of any cycle is equal to the length of the cycle