How can you denote a numeric variable in SAS?

In SAS, a numeric variable is one that is recognized as containing numerical data rather than character data. To denote a numeric variable, you simply assign it a number. This means that you can directly input numeric literals into a SAS data step or data set without any special notation. For example, you can create a numeric variable by using a statement like variable_name = 5;, where variable_name will be identified as a numeric variable because it is assigned a numeric value.

The other options do not correctly denote a numeric variable. Using a dollar sign indicates that the variable is a character variable (often used for formatted output). Enclosing a value in quotes signifies a character string, which SAS treats as a character variable irrespective of its numeric content. Thus, simply assigning a number is the appropriate method for creating a numeric variable in SAS.