It isnt difficult to do. Assuming you are already familiar with instances.
In a numericField exit event, add some if logic along the lines of this:
• This is a basic way of doing this to make it easier to understand, but you could more elegantly do it with a loop. A loop will also mean you dont have to have an if for every number. You could also use switch instead of if.
• This will always add the numbers of rows specified to the bottom of the table. It wont make the table the rows specified. ie. if you have three rows and specify three rows, the table with now have 6. If you exit the numericField again, the table with have 9 rows and so on.