# Number in a mutable variable

We can make a variable mutable by adding the [mut](https://doc.rust-lang.org/std/keyword.mut.html) keyword to the declaration.
In this example we use numbers as strings have addition constraints.

{% embed include file="src/examples/variables/mutable-number/src/main.rs" %}

The output:

{% embed include file="src/examples/variables/mutable-number/out.out" %}


---

* let
* mut


