I appreciate your help but I think my situation is a little different than you think. I have a column of cells. Each cell calculates the cost of fuel used during a flight by a simple formula (hours flown*fuel consumption per hour*(fuel price/gallon). The cell that contains the fuel price/gallon ie: $t$2, is used in the formula as a absolute reference in place of entering the fuel price into the formula. (This makes it easier for the secretary to just change the cell that says "fuel price"(T2). Is there a way to accomplish this idea without recalculating all the past "cost of fuel". Can the value in the cells be protected once a calculation is done so the past values will be accurate with the past price per gallon and not the current price per gallon?