Summarizing Column Data
The summary row provides an easy way to perform basic operations on the data in a column and display the results. The summary row is located at the bottom of table view and at the bottom of simple list fields and related data fields.
To show or hide the summary row, choose View > Show Summary Row or Hide Summary Row. Or, clicSummary row icon.
Depending on the field type, the following summary functions are available.
 
You can use the Count function on any type of field. You can use the Sum, Average, Minimum, and Maximum functions on fields of the following types: Number, Currency, Duration, Rating, Automatic Counter, and Calculation (when the result is number, currency, or duration). You can also use the Minimum and Maximum functions on Date and Time fields.
To calculate a summary for a column:
Click in the summary row of the selected column, then choose a function from the pop-up menu. The name of the function and the results are displayed in the summary row.
Choose Sum in the summary row to calculate the total of the amounts listed in the selected column
When you do a search or an Advanced Find, the summary is recalculated based on the records that are found.