In computers we use: decimal constantly, hexadecimal daily, octal weekly and binary monthly. Decimal is base 10, hexadecimal is base 16, octal is base 8 and binary is base 2.
To convert binary to decimal, simply add the magnitudes of the digits that are set.
You would want to configure to show file extensions for a couple different reasons. First if you have a couple files and they are have the same name but one is say a PDF while the other is a DOCX file. Another reason, mainly for development, programming, graphic design, ect. you may need to know different extensions to determine the language a file is written in such as PHP, HTML, ect. or to know an image type such as jpg, png, gif, ect.
Be persuasive, have form, and know what you are talking about. I would recommend using MELCON. You can learn more about MELCON with this link. http://melcon.weebly.com/