The environment is always available as a map from the function environment. You can find out what values are defined by typing [environment]. Although the help function will display it better.
You might notice the bootstrap contains the map Math which contains mathematical functions. We can make use of these like this:.
The latter example evaluates inside Math so no other names are defined apart from those in Math. This is a problem if we want to use a function like + which is builtin. A solution is to use the let function add the names defined in Math to the current environment.