A datasheet can contain a maximum of 4,000 rows and 4,000 columns. A chart can contain up to 255 data series, with up to 4,000 data points in a data series.
How?
To insert blank rows, select rows immediately below where you want to insert the new rows. Select the same number of rows as you want to insert.
To insert blank columns, select columns immediately to the right of where you want to insert the new columns. Select the same number of columns as you want to insert.
How?
If you selected a range, click Shift cells right or Shift cells down.