Microsoft Excel give the facility to repeat information in many cells throughout a worksheet.
The following process show the Automatically filling. In this example we fill the The SNO from 1 to 10 in Column:

Select any cell where you want to write the first Number. In my example A3 in above image.
Type 1 in cell A3.
Now click and hold Fill Handle ( black square in the lower-right corner of the Cell which is circle with red color in above image This small black square is called the fill handle).
Now Drag the fill handle Downwards up to 10 cell. Note that the Auto Fill Options button appears.

Click the Auto Fill Options button. The Auto Fill Options menu appears.
Choose the Fill Series radio button. The cells fill as a series from 1 to 10.

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