Every now and then I might need to make a special character that isn't on the keyboard. Like the copyright symbol. To do this I would need to insert a Alt Code. So called because you have to press and hold on the Alt Key and then a series of numbers to produce certain symbols orcharacters.
These non-ASCII special characters that are not present in the character set on a normal QWERTY keyboard. So If I wanted the copyright symbol I would hold down on the Alt key and then press the corresponding number which is 0169. So, Alt + 0169 = ©
Note: when you press the numbers you have to use the Number Keypad. When you finish typing the number, release the Alt key and your symbol should appear. Results may vary depending on your word processor, font used.
For example here's the symbol for pi:
This is in OpenOffice but the results are mirrored in LibreOffice. It looks proper in Times New Roman font. Verdana makes it look like an unfinished rectangle. Arial Black makes it look like to T's joined together at the top.
Some keyboards might not have a number pad. Then it's recommended to look for a NumLK key and press Fn + NumLK and type the number.
I have a Logitech K400r wireless keyboard that has a trackpad instead of a number pad, hooked up to my Gateway desktop. It doesn't have a Number lock key at all.
In this case you can use the Character Map. Type Character Map in search and click on it when it appears. Pick a font at the top, depending on what symbol your searching for. Find the symbol you want and double-click on it. You'll see it added to the Characters to copy line at the bottom of the Character Map window and then select Copy. Now go to your document and paste it in.
For a more complete list of codes: https://altcodeunicode.com/