Converting a number with decimals to fraction

I was have joined this yahoo group which talks about Excel topic. Somebody asked if he is able to convert a number with decimals to a fraction. As I explore the format cell, I noted that there is this category that could convert the number to fraction. Not only that, it also gave options on whether to convert the number to fraction based on on 1 to 3 decimal places. There are also other options. See this diagram for more details.