Count row numbers only for data in a table

[numfon_naka]

want the number of rows to be counted per table
When starting a new table count 1 2 3

[dbaum]

It's unclear what specifically you're seeking to accomplish. If you're indeed referencing AppSheet, your screenshots may be confusing the issue since they don't represent spreadsheet data that could be used as an AppSheet table, which is what you ask about.

In a generic sense, the answer to your question is:

COUNT({expression that returns table's rows})

In your specific scenario, something like one of the following might provide what you need.

COUNT(Table[Row ID])

COUNT([Related B])

If you're not asking about tallying the total number of rows but rather perhaps about assigning a sequential index number to each row, start with the information explained in  Serial Numbers, If You Must - Google Cloud Community .