Most of the time you would just use : 2^3 unless you are using a word processing program that allows the use of the extra symbols. For Example in WORD you would do the following :
1 Open Microsoft Word and open a new document.
2 Type a number and the number you would like to appear as an exponent.
For example, if you want to write 7 squared, type 72.
3 Highlight the number you would like to appear as an exponent (in our example, 2).
4 Right-click on the highlighted number and click on "Font." In the "Font" window,
check the box next to "Superscript" in the "Effects" section. Click on the "OK" button.