Permutations

Permutations are about reordering. The word mutation means a change. Permutations are about how many ways the order of something can be changed.

Let’s look at a simple example.

How many ways can we order the three blocks?

There are three positions for each block.

How many ways can we fill the first position?

We can put the red, yellow or blue block there, so three. Let’s say we put the blue one there.

Now, we have the red and yellow blocks left. How many ways are there to fill the second position? Two. Red or yellow. Let’s say we put the red one there.

Now there is just the yellow block left so there is only one way to fill the last position.

In total there are ways to arrange the blocks.

Here are all of the ways