How many unique ways are there to arrange the letters in a word OPAL.

24.

Step-by-step explanation:

We can use the factorial function to find the number of unique arrangements in a word.

There are 4 unique characters in 'OPAL'. As such, 4! = 24.

In the case that there were repeating characters, such as 'OPALA', then we would divide by the factorial of the number of repeating letters. That looks something like this:

Hope this helped.