Automatically number rows
Unlike other Microsoft 365 programs, Excel does not provide a button to number data automatically. However, you can easily add sequential numbers to rows of data by dragging the fill handle to fill a column with a series of numbers or by using the ROW function.
Fill a column with a series of numbers
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Select the first cell in the range that you want to fill.
First Cell
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Type the starting value for the series.
Value for the Series
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Type a value in the next cell to establish a pattern.
Establish a pattern
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Select the cells that contain the starting values.
Starting Values
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Drag the fill handle 
across the range that you want to fill.
Fill Handle
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Use the ROW function to number rows
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In the first cell of the range that you want to number, type =ROW(A1).
Row numbers
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The ROW function returns the number of the row that you reference. For example, =ROW(A1) returns the number 1.
Row Function
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Drag the fill handle 
across the range that you want to fill.
Fill Handle
To enter specific sequential number codes, such as purchase order numbers, you can use the ROW function together with the TEXT function.
For example, to start a numbered list by using 000-001,
1. Select the first cell in the range where you want your sequential numbers to begin.
Cell range
2. Enter the formula: =TEXT(ROW(A1),"000-000")
Text
3. Press Enter. The first code (000-001) appears in the cell.
First Code
4. Drag down the fill handle to the end of the range. Excel will fill in the sequence automatically (000-002, 000-003, and so on).
Fill Code