I thought that the answer was $\displaystyle 5!^5$, but was told this was wrong. Could someone step me through how to do this?Quote:

The integers 1-25 are arranged in a 5x5 array (we use each number from 1 to 25 exactly once). All that matters is which numbers are in each column, and how they are arranged in the columns. It does not matter in which order the columns appear. How many different such arrays can be formed?

Thanks!