Perform the indicated calculation. \[ { }_{50} P_{2} \]

Step 1 ：The problem is asking for the permutation of 50 items taken 2 at a time. The formula for permutation is given by: \[P(n, r) = \frac{n!}{(n-r)!}\] where \(n!\) is the factorial of \(n\), \(r\) is the number of items taken at a time, and \((n-r)!\) is the factorial of \((n-r)\).

Step 2 ：In this case, \(n = 50\) and \(r = 2\). So, we need to calculate: \[P(50, 2) = \frac{50!}{(50-2)!}\]

Step 3 ：Final Answer: The permutation of 50 items taken 2 at a time is \(\boxed{2450}\).