There are 6 items in column A and 6 items in column B. A student is asked to match each item in column A with an item in column B. How many possible (correct or incorrect)answers are there to this questions?

Answer

720

Explanation

First item in column A can be matched with any of the 6 items in column B.
Thus, the first item of column A can be matched in 6 ways.
Similarly, 3rd item of column A can be matched in 5 ways.
Similarly, 3rd, 4th, 5th and 6th items of column A can be matched in 4, 3, 2 and 1 ways respectively.
By the fundamental principle of multiplication, the required number of ways `=(6xx5xx4xx3xx2xx1)=720.`