Click Start > All Programs > Accessories > System Tools and select Character Map. This will load up the Windows XP version of the Character Map tool. The Character Map tool is used to express a variety of characters on the computer. You can a wide variety of characters here, some alphabetical, some scientific, some mathematical and even some religious.
Now, you're going to want to search through the different fonts to find the different mathematical symbols you are looking for. Different fonts contain different mathematical symbols. For example, the common '÷' symbols can be found under the font "Raavi", will the more complicated symbols like squared and cubed can be found elsewhere.
Once you find the mathematical symbol you want to copy, double click on it and it will copy to the "characters to copy" space. Once you have selected all of the mathematical symbols that you want to copy, simply click the button in the Character Map tool labeled as "Copy".
In order to paste these characters somewhere else. Simply click into the text box that you want to copy them into and press and hold down 'CTRL' and tap the 'v' key.