1. In a new column, say column B, enter the following formula in cell B1: =IF(ISBLANK(A1),0,A1)
2. Drag the formula down to fill the rest of the cells in column B.
3. Now, use the AVERAGE function on the range B1:B6 instead of A1:A6. This will treat the blank cells as zeros and give you the correct average.

Alternatively, you can use the AVERAGEIF function to achieve the same result without having to create a new column:

1. Use the following formula: =AVERAGEIF(A1:A6,"<")
2. This formula will only consider cells that are not blank in the range A1:A6 and treat the blank cells as zeros.