Permutations part two

Now we have five blocks

If we have three places to fill again then how many possible permutations are there?

We can fill the first place in five ways by choosing red, yellow, blue, green or purple.

Lets say we choose purple

Now we can choose red, yellow, blue or green for the second position. There are four colours we could choose but lets choose blue.

Now we are left with three choices for the final position. Lets choose yellow.

In total there are ways to arrange the blocks.