If you need to add numbers to cells in a column or row, use Excel’s auto-fill feature. To start counting at one, enter 1 in the first cell and 2 in the second cell. Then, select both cells and drag the fill handle (square in the bottom-right corner) down a column or across a row to fill the remaining cells.
To use a different numbering scheme, for example, 10, 20, 30, and so on, enter the first two numbers you want to use in the first two cells, then use the fill handle. Excel should recognize your numbering pattern and comply.