To add this
Enter this
\rm text
To combine several fonts, use {\rm text} to specify Roman.
\it text
To combine several fonts, use {\it text} to specify Italic.
Extra space
~ or \;
\cdot or \times
Use \cdot for multiplication between variables.
For example: w = Fd is F \cdot d
If explicit multiplication needs to be emphasized, do not use \times.
Use × (\times in TeX) for scientific notation, dimensional analysis, and equations involving words.
Subscript
Example: 
_ subscript for single digit subscripts
-OR-
_{subscript} for double digit subscripts as in C_{12}
Superscript
Example: 
^ superscript for single digit superscripts
-OR-
^{superscript} for double digit superscripts as in C^{12}
Stacked superscripts and subscripts
Example: 
Offset superscripts and subscripts
Example: 
_ {subscript} ^
-OR-
{^{superscript}}{_{subscript}} as in HSO{_{4}}{^{-}}
\lower_Greek_letter
For example: \alpha
Uppercase Greek letter
\upper_Greek_letter
For example: \Alpha
Fraction
{x \over y}
-OR-
{\frac {x}{y}}
Infinity symbol
Vector arrow over xy
Chemistry reaction arrow
Chemistry equilibrium arrow
