Select the same number of existing rows as the number of rows you want to add
Right-click the selected row headers
Click Insert
Use the Home tab, then click Insert, then Insert Sheet Rows
To add multiple non-adjacent rows, select each row header while holding Ctrl
Press Ctrl + Shift + + to insert rows after selecting the row range
In a table, press Tab in the last cell to add a new row
Copy a block of blank rows and paste it where needed
Use the Name Box to select a range of rows, then insert them at once