Examples:

$\begin{picture}(380,1)(0,0) \put (0,0){\framebox{(}380,1)} \end{picture}$

2'100 : 4 in binary notation.
0b100 : 4 in binary notation.
8'73 : 59 in octal notation.
0o73 : 59 in octal notation.
16'f7: 247 in hexadecimal notation.
0xf7: 247 in hexadecimal notation.
0'a: the code of 'a', which is 97.
0'\\: the code of '\', which is 92.

$\begin{picture}(380,1)(0,0) \put (0,0){\framebox{(}380,1)} \end{picture}$

A floating-point number consists of an integer (optional), then a decimal point, and then another integer, optionally followed by an exponent. For example, 23.2, 0.23, and 23.0e-10 are valid floating-point numbers.

Neng-Fa Zhou 2013-01-25