# Declare a new identifier $x and bind it to a new mutable Scalar container:
my $x;

# Assign a value into the Scalar:
$x                # An LHS reference to a Scalar returns the Scalar.
   =              # = is assignment. The LHS decides what to do with it.
     9.9;         # Creates a new immutable Rat.

# VAR macro returns what the identifier is bound to:
say $x.VAR.^name; # Scalar -- the type of variable bound to $x.

# All other uses of $x or a Scalar on RHS return the value assigned into the Scalar:
say $x;           # 9.9
say $x.^name;     # Rat -- the type of the value assigned into the Scalar.
$x *= 2;          # This is equivalent to ...
$x = $x * 2;      # ... which assigns result of RHS expression into Scalar on LHS.
say $x;           # 39.6