Excel's Formula - sisman

Chapter 2: Basic Facts about Formulas 61
When you enter a formula that contains a circular reference, Excel displays a dialog box with two
options: OK and Cancel.
Normally, you’ll want to correct any circular references, so you should click OK. After you do so,
Excel inserts tracing arrows and displays the Help topic for circular references. The status bar displays
Circular References: A3, in this case. To resolve the circular reference, choose
Formulas➜Formula Auditing➜Error Checking➜Circular References to see a list of the cells
involved in the circular reference. Click each cell in turn and try to locate the error. If you cannot
determine whether the cell is the cause of the circular reference, navigate to the next cell on the
Circular References submenu. Continue reviewing each cell on the Circular References submenu
until the status bar no longer reads Circular References.
In a few situations, you may want to use a circular reference intentionally. Refer to
Chapter 16 for some examples.
Instead of navigating to each cell using the Circular References submenu, you can click
the tracer arrows to quickly jump between cells.
If you ignore the circular reference message (by clicking Cancel), Excel enables you to enter the
formula and displays a message in the status bar reminding you that a circular reference exists. In
this case, the message reads Circular References: A3. If you activate a different worksheet
or workbook, the message simply displays Circular References (without the cell reference).
Excel doesn’t warn you about a circular reference if you have the Enable Iterative
Calculation setting turned on. You can check this in the Excel Options dialog box (in the
Calculation section of the Formulas tab). If this option is checked, Excel performs the
circular calculation the number of times specified in the Maximum Iterations field (or
until the value changes by less than .001 — or whatever other value appears in the
Maximum Change field). You should, however, keep the Enable Iterative Calculation
setting off so that you’ll be warned of circular references. Generally, a circular reference
indicates an error that you must correct.
When the formula in a cell refers to that cell, the cause of the circular reference is quite obvious
and is, therefore, easy to identify and correct. For this type of circular reference, Excel does not
show tracer arrows. For an indirect circular reference, like in the preceding example, the tracer
arrows can help you identify the problem.
Goal Seeking
Many spreadsheets contain formulas that enable you to ask questions, such as, “What would be
the total profit if sales increase by 20 percent?” If you set up your worksheet properly, you can
change the value in one cell to see what happens to the profit cell.