Permutations and Combinations

This week we learned about permuatations and combinations. Permutationa and combinations are formulas used to find different ways something can be ordered. The difference between a permutation and combination is that you use a permutation when the order is important and you use a combination when the order is NOT important.

Some things to know:

• 
  
  The formula for a permutation is n!/(n-r)!


• 
  
  The formula for a combination is n!/(n-r)r!


• 
  
  Your n will ALWAYS be larger than you r.

Let's do some examples to help you better understand.

Example 1: 5P3

5P3=5!/(5-3)!

=5!/2!

=5*4*3*2*1/2*1

= 60

Example 2: 5C3

5C3=5!/(5-3)3!

=5!/2!3!

=5*4*3*2*1/2*1*3*2*1

=20/2

=10

And there you have it(: