Using the letters in the word addition, find the number of permutations that can be formed using 3 letters at a time.

84 words.  

Step-by-step explanation:

We are asked to find the number of permutations that can be formed using 3 letters at a time, using the letters in the word ADDITION.    

Since order matters in permutations, so the repetition of same words is not allowed.    

The number of permutations of n objects taken r at a time is determined by the following formula:  

Since 2 letters are repeated so we can choose 3 letters from 8 letters as:

Therefore, there are 84 words that can be formed using 3 letters at a time.