Premutations and Combinations

Permutations- A permutation is a order of numbers where the order does matter
Combinations- A Combination is a order of numbers where the order does not matter

A combination lock is a perfect example of a Permutation as it is three order number line where the numbers have to be in the right order to open the lock.

If your combo is 23-67-9 you can only put it in as this order if you put 67-23-9 the numbers are the same but the order is not making it impossible to open your locker.

The order through which you put fruit into a smoothie is a combination
If Apples are 1
Banannas are 2
Peaches are 3
The order can go many ways
123
132
321
213
231
312

In other words a permutation is an ordered combination

The above formula is for Permutations without repitition the below fomule is for combinations without repitition.

where n is the number of things to choose from, and you choose r of them       (Order does not matter)

For things where repitition is allowed the formulas are as follows

Permutations is simply N to the exponent R where N is the number of things to choose from and R is how many you will choose

Combinations where repitition is allowed is shown as the formula below

where n is the number of things to choose from, and you choose r of them
(Repetition allowed, order doesn't matter)

All information was taken from the link below the above descriptions and formulas are a short sumamry of the site the site as well provides real world examples

http://www.mathsisfun.com/combinatorics/combinations-permutations.html