To swap two numbers in Excel, first select the cells containing the numbers you want to swap. Then, click the "Home" tab on the ribbon. In the "Clipboard" group, click the "Copy" button. Next, select the cell where you want to paste the copied numbers. Finally, click the "Paste" button in the "Clipboard" group.

You can also use a shortcut to swap two numbers in Excel. First, select the cells containing the numbers you want to swap. Then, press and hold down the "Ctrl" key on your keyboard. While holding down the "Ctrl" key, press the "X" key. This will cut (or delete) the selected cells. Next, select the cell where you want to paste the cut cells. Finally, press and hold down the "Ctrl" key on your keyboard. While holding down the "Ctrl" key, press the "V" key. This will paste (or insert) the cut cells.