How many unique combinations of 25-items from a 50-item test pool?

I have a pool of 50 questions. My quiz will consist of 25 questions selected from that pool. How many unique 25-item tests can there be?

I used the formula: C=N!/n!(n-N)!

That means C=50!/25!(50-25)! = 50!/(25!)(25!) = 126 trillion.

That just seems impossibly large and my instincts are telling me that can’t be right. What am I doing wrong, or is 126 trillion right in spite of my so-called instincts?