In Elixir, floats are written with a decimal point, with digits before and after it, meaning that .1 is not a valid float in Elixir (as it is, for instance, in JavaScript). In Elixir, you have to be explicit and write the leading 0—so in this case, you'd write 0.1. Here's an example of the multiplication of two floats:
iex> 0.1 * 0.5 0.05
You can also write floats using the exponent notation, as shown:
iex> 0.1e3 100.0
Floats are represented in IEEE 754 double precision, which yields between 15 to 17 significant decimal digits. As usual, you should take care when comparing floats for equality.
Beware that the division operator ( /) always returns a float, even if the result of the division could be an integer:
iex> 4/2 2.0
If you want to circumvent this behavior, use the auto-imported div function from the Kernel module. Also, if you want to get the remainder of a division, use the rem function.