A calculated field can also be created by navigating to the Menu/Analysis and selecting Create Calculated Field.
A calculated field can use any of the Tableau defined functions such as
Exercise: Use Tableau sample data source Sample- Superstore.xls located under \My Tableau Repository\Data sources. Use the Orders Datasheet. Create a calculation for Sales with Discount. Use the formula:
Sales * Discount.
Table calculation can also be created just like regular calculation but will use the Table calculation functions.