I have a column of data. Each cell in the column represents a new day. So the 1st cell is for the 1st day and the Nth cell is for the Nth day. I want to add a 2nd column where the Nth cell in that column displays the average of the first N cells in the 1st column. I want to enter this formula once and then drag it down to the bottom of the column so that the entire column is 'filled' with the proper formula.

Currently, when I specify the average function like `AVERAGE(A1:A5)`, dragging that formula increases both the starting and the ending cell indices in the new filled formulas. For example, two cells down from the cell above I might have `AVERAGE(A3:A7)` when what I want is `AVERAGE(A1:A7)`.

Example:
Col1 __ Col2
7 __ __ 7
8 __ __ 7.5
7 __ __ 7.333
9 __ __ 7.75

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Use the following notation:

`=AVERAGE(A\$1:A5)`

Copying this formula, will yield:

`=AVERAGE(A\$1:A7)`

Absolute references explained:

• \$A\$1; Both the column and row reference are fixed.
• \$A1; Only the column reference is fixed.
• A\$1; Only the row reference is fixed.

Reference: Absolute reference

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