Following assumptions:
1. Your "balance" column is column "J"
2. You are currently having 10 rows
3. The 1st row contains the column headers
4. Rows 2 to 11 contains the data rows
5. The worksheet is "sheet1"
Then the following formula will give the last column value in column J
=OFFSET(Sheet1!K1,(COUNTA(Sheet1!J2:Sheet1!J11)-1),-1)
Please note:
The formula will not work if any blank entry is there in the "Balance" column
As with all excel formulas, in order for the "CountA" formula to update automatically, to add a row, you need to insert a row before the last row (within the range). If you add a new row after the last row (outside the range) then you will need to manually update the reference in the "CountA" range.