This is quite easy to do, hold down the "Alt" key and type in the 4 figure ASCII code .
I am using US and UK keyboards, this might not work on all configurations.
Other useful ones that I often use are listed below.
Ä 0196; ä 0228; º 0186; « 0171; ¼ 0188;
Ë 0203; ë 0235; ¹ 0185; » 0187; ½ 0189;
Ö 0214; ö 0246; ² 0178; ¤ 0164; ¾ 0190;
Ü 0220; ü 0252; ³ 0179; µ 0181; ± 0177;
€ 0128; ß 0223; ø 0248; § 0167; ÷ 0247;
Please note :-
This is from a list I comprised myself and is not copied from a website.