Efficient approach of selecting large amount of rows in an Excel file

One thing I do is press F5 (on Windows - brings up the "Go To" menu) and in the Reference section type the address of the range I want to select. For instance, to select the first 100,000 rows, type 1:100000 (or A1:D100000, etc.).

You can also do various things like hitting Shift+Space and Ctrl+Shift+Down assuming 100000 is the end and your range is contiguous, Ctrl+A to select the entire used range, etc.

I simply use the End key. Start with A1 selected. Hold down Shift, then press End and then →. Then (while still holding Shift) press End again and then ↓.

This should select everything in a very small number of key strokes. However if there are gaps in your data you may have to press End then ↓ until you have everything.

For Excel (Windows 10, Office 365 at least) this is very easy.

1. Click to select a cell within your table of data
2. Press the "End" key to tell Excel that you want to select all cells until the end of the table of data
3. Now press and hold the "Shift" key and then press one of the four arrow keys

All the cells from the cell you first selected to the last cell in the arrow's direction should now be selected.

You can also begin at step 1. and select a group of cells.

I have a Mac, using Version "16" and do not know where the "GoTo" menu is, so here's an alternative if you need to delete a large number (but not all) of the rows. Click on the first row to select it, scroll down to the row that is the bottom of the range you want to delete. Do a shift click on that row - this will highlight all the rows you want to delete. Click on the Delete menu item in the Edit menu.