In addition to the built-in functions you can use to compare values in a query, you can use the Expression Builder to create your own calculations using arithmetic operators. By clicking the operator buttons you want to use and entering constant values as needed, you can use the Expression Builder to include expressions in a query. For example, to determine fees based on a contract amount, you can create an arithmetic expression in your query to compute the results. When you run the query, Access performs the required calculations and displays the results. You can also insert functions, such as AVG and Count, to perform other operations. When you insert a function, <<expr>> appears in parentheses, which represents an expression. Select <<expr>> and replace it with a field name , which you can select in Expression Builder.
Create a Calculated Field