What is the difference between combinations and permutations?
It depends of whether the order is important.
Let's say you choose a committee of three to represent your class of 30 students:
For the first member you have
For the second you have
For the third you have
For a total of
Now this is assuming that the order of choice is relevant: the first one will be called 'president', the second will be 'secretary' and the third will be just 'member'.
If this is not the case (all three are equal) then the order in which they are picked is not important.
With three picked there are
So: combinations= permutations divided by orders
Or, in our example:
You will find the functions
where -in this example- you would do
There is also a function called
And you will notice that: