When to use permutation/combination in a given question of permutation and combunation?

**Permutation:**

Each of the arrangements which can be made by taking some or all of a number of things is called a permutation. For example, if there are three objects *x, y *and *z, *then the permutations of these objects taking two at a time are *xy, xz, yx, yz, zx *and *zy. *In permutation the order of arrangement is taken into account. When the order is changed, a different permutation is obtained. The notation of permutation is given by

**Combination:**

Each of the different selections made by taking some or all objects irrespective of their arrangement is called combination. For example, if there are three objects *x, y *and *z, *then the combinations of these objects taking two at a time are {*x,y*}, {*y,z*} and {*z,x*}*. *In combination the order of arrangement is not taken into account.

In simple language,

⇒ If the order does matter, it is permutation.

⇒ If the order doesn't matter, it is combination.

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