Note: If the database module is not displayed, open it with the ribbon command Mailings | group Recipients | Select recipients.
The record number is a sequential number used to number the records. The first record has the number 1, the tenth 10, etc. The record number is always displayed at the bottom left in the status bar in the database module.
In the database module, you will find the command Select 
| By record numbers in the group Records. This allows you to select or deselect a range restricted by record numbers.
The program displays a dialog box in which you specify the range of record numbers to be selected. The entire database is automatically specified. For example, enter 10 and 20 if you want to select the records 10 to 20 inclusive.
If you then click on the Select button, all records in this range will be selected; if you click on Deselect, on the other hand, they will be deselected, that is, excluded from the selection.