To evaluate the permutation \({ }_{5} \mathrm{P}_{4}\), we need to use the formula for permutations, which is given by:
\[
{ }_{n} \mathrm{P}_{r} = \frac{n!}{(n-r)!}
\]
Here, \(n = 5\) and \(r = 4\). We will calculate the factorial of 5 and the factorial of (5-4), then divide the two results.
Step 1: Identify the Permutation Formula
To evaluate the permutation \({ }_{5} \mathrm{P}_{4}\), we use the formula:
\[
{ }_{n} \mathrm{P}_{r} = \frac{n!}{(n-r)!}
\]
where \(n = 5\) and \(r = 4\).
Step 2: Calculate Factorials
Calculate the factorial of \(n\) and \((n-r)\):
\[
5! = 5 \times 4 \times 3 \times 2 \times 1 = 120
\]
\[
(5-4)! = 1! = 1
\]
Step 3: Apply the Permutation Formula
Substitute the factorial values into the permutation formula:
\[
{ }_{5} \mathrm{P}_{4} = \frac{5!}{(5-4)!} = \frac{120}{1} = 120
\]
Final Answer
The value of \({ }_{5} \mathrm{P}_{4}\) is \(\boxed{120}\).