floating point constants

Similar to integer constants, floating point constants are used to make code more readable. Floating point constants are swapped at compile time for the value to which the expression evaluates.

Examples:

n = .005; 

Floating point constants can also be expressed in a variety of scientific notation. 'E' and 'e' are both accepted as valid exponent indicators.

floating-point   evaluates to:      also evaluates to:
  constant 
 
   10.0	             10
  2.34E5          2.34 * 10^5             234000
  67e-12        67.0 * 10^-12         .000000000067

Source: arduino.cc