Question

Find the number of distinct arrangements of 12 letters in REENGINEERED. Two of the same letter are considered identical

Answer 1

We have to find the number of distinct arrangements of 12 letters in REENGINEERED.

First, we list the number of unique letters we have and its frequency. We have:

• R: 2

,

• E: 5

,

• N: 2

,

• G: 1

,

• I: 1

,

• D: 1

for a total of 12 letters.

We can then calculate the number of distinct arrangements as the the total number of arrangements divided by the permutations that are repeated.

This can be expressed as the factorial of 12 divided by the product of the factorial of the frequencies of each letter (the letters that have a frequency of 1 will not affect the result so they are ignored for the denominator):

`n=(12!)/(2!5!2!)=(479001600)/(2*120*2)=(479001600)/(480)=997920`

Answer: there are 997,920 distinct arrangements.