All scalar variables are introduced by the $ symbol. The actual name of the variable may include any of the characters in the ASCII set,
alpha (a-z, A-Z), numeric (0-9), and the underscore ( _ ) with the exception that the first character may not be numeric.
The $ symbol is used whenever the variable is referenced:

# initialize  a scalar to a string
  $food = "spaghetti";
# initialize an integer number
  $quan = 4;
# initialize a floating-point number
  $price = "2.49";
# initialize a mathematical result
  $total = $quan * $price
# pass a scalar to print
  print "$food\n";
# initialize one scalar from another
  $meal3 = $food;          

In the above example, the string spaghetti is a scalar value, as is the number 4. The result of the expression, $quan * $price, is also a scalar value.

Click the Quiz link below to take a short multiple-choice quiz on scalars. Understanding the basic use of the scalar type will allow us to build on that knowledge in the next lesson by learning about the differences between numeric and string context.
Perl Scalar Type - Quiz