Using row numbers

The Row Number facility allows you to specify a number that increments as each section is processed. The start number can either be entered at run-time as a parameter, or retrieved from a data field value.

You can increment a row number based on the change of a value of a field.

From the special fields pane, drag a row number on to the report. Right-click the field Properties and select Field Settings. The Row Number dialog is displayed. A number is incremented either on each change of the reset level defined in the dialog, or by a page break.
Specify this information:

Name

The name for the row number is determined automatically.

Increment

Specify the value for the number to be incremented by. The default is 1. Enter the value or use the browse button to display the Value Expression dialog. Click Add Case to open the Value Expression dialog where you can define that the increment only applies where specific filters are applied at runtime.

Increment on change of: Page

Select this radio button if you require the number to be incremented on every page break.

Increment on change of: Group

Select this radio button if you require the number to be incremented on the change of a specified group. When this option is selected, the adjacent drop down list is enabled where you can pick from the list of existing 'order by' groups.
Save your changes.