One of the classic problems in probability theory is the “matching problem.” This problem has many variations and dated back to the early 18th century. There are many ways to describe the problem. One such description is the example of matching letters with envelopes. Suppose there are 25 letters with 25 matching envelopes (assume that each letter has only one matching envelop). Further suppose that the secretary stuffs the letters randomly into envelops. How many letters will typically be placed in the correct envelope?