Updating multiple records by formula

I have a table that includes a column titled "RowNumber". When I insert a record in the middle of the table, I would like RowNumber to be incremented by 1 for each record after the insertion point. The brute force approch would be to read each following record, calculate a new value for RowNumber then update the record. I was wondering if there was a better way that would allow me to update multiple records at once.

Thanks in advance.