Here's a very easy way that I've found with which you can easily copy same data across multiple cells.
If you are COPYING TEXT, then you don't need to press any keys. But if you would like to COPY Numbers across cells, then press CTRL key while dragging the mouse, as shown in the video.
If you are COPYING TEXT, then you don't need to press any keys. But if you would like to COPY Numbers across cells, then press CTRL key while dragging the mouse, as shown in the video.