Use the keyboard shortcut Ctrl+Enter to quickly fill multiple cells with a value or formula.
For example, you may want to enter a bunch of 0's (zeros) in a range of cells. Or, you want to apply the same formula to a range of cells without changing the cell formats.
1. Select a range of cells
2. Enter the value or formula
3. Instead of pressing Enter afterwards, press Ctrl+Enter to fill the entire range of cells.
This is basically an alternative approach to entering a value in a single cell and then copying that cell and pasting the value or the formula. Using Ctrl+Enter does not copy formatting.
If you are using a relative reference in your formula (like =A1), then the formula in the other filles cells will be the same as if you entered the formula in just the one cell and then copied that cell to the other cells in the range. If you want the formula reference to not change when you use Ctrl+Enter, you will need to use an absolute reference (like =$A$1).