How many unique ways are there to arrange the letters in the word PRETTY?

1 Answer
Mar 27, 2018

#360#

Explanation:

Because we have a repeated letter we have to divide this out.

The permutations of #color(white)(0)^6P_ 6#=

#6! =6xx5xx4xx3xx2xx1#

The repeated letters have #2!# permutations.

So for unique arrangements we need:

#(6!)/(2!) =(6xx5xx4xx3xx2xx1)/(2xx1)#

#= (6xx5xx4xx3xxcancel(2xx1))/(cancel(2xx1))=6xx5xx4xx3=360#