There are 16 different colors. How many different combinations of 2 are there? Not repeating combinations.

Question

There are 16 different colors. How many different combinations of 2 are there? Not repeating combinations. Example: Blue and green would be the same as green and blue therefore green and blue would not be a valid combination.

Answer 1

Christopher,

The formula for this is nCr =         n!        

                                             r!(n-r)!

 

where C stands for combination, n is the total population, and r is the desired sample.

Remember the 4! = 4*3*2*1 = 24

 

So for this problem, ₁₆C₂ =      16!       = 120

                                          2!(16-2)!

 

Many TI calculators have a button for this function so you don't have to punch the formula every time.