When spreadsheet users hear the term circular reference, they immediately think of an error condition. Most of the time, a circular reference occurs by accident ù it's a formula that refers to itself. But circular references can serve a useful purpose. For example, to sum the values in range A1..A10, you could enter @SUM(A1..A10) in cell A11. But if you inserted a new row directly above row 11, you would need to change the formula so the sum included the new row: @SUM(A1..A11). To eliminate the need to change your formula when you insert a new row above the SUM formula, use this formula in cell A11: @SUM(A1..A11)-A11. The circular reference produces a result that's larger than it should be, but then the result is subtracted from itself so in the end it displays the correct answer. The advantage, of course, is that the references in this formula adjust automatically when a new row is inserted above the formula.