A useful website listing all the ascii codes available.
To use them practically;
1. Find the character you want to use from the “Symbol” column.
2. Press and hold the “Alt” key and use your number pad to type the digit(s) listed in the “DEC” column of that character’s row.
This will return the relevant character to wherever you are currently typing.
Some codes I find useful; (“Alt” + the following on the “Num Pad”)
0128 = €
0162 = ¢
0163 = £
0165 = ¥
0064 = @
0153 = ™
0169 = ©
0174 = ®
0177 = ±
0215 = ×
0247 = ÷
0186 = º
0185 = ¹
0178 = ²
0179 = ³
0191 = ¿