What’s Going On Inside An Excel Formula

Q. Sometimes when I’m dealing with a long, complex formula in Excel, and my answer doesn’t look right, I double-check the formula. But when a formula is very big, it’s hard to locate the error. Is there some way I could look inside the formula to see how each step is being calculated?

A. Excel has such a tool. To access it, highlight the formula you want to check and click on Formula Auditing and Evaluate Formula . Excel displays this dialog box with your formula:

Excel immediately begins to calculate the first part of the formula (the portion to the left of the underlined section). Each time you click on the Evaluate button, Excel calculates the next portion in the formula, from left to right. Thus you can look at the results calculated by each part of the formula. Don’t worry, nothing in the formula changes as you move around—only the intermediary results. When you’re finished, click on Close .

There’s also a simple version of Evaluate Formula —a way to test a formula before you commit it to a cell: Type a formula in Excel’s Formula bar (the space next to fx), for example:

But instead of pressing Enter, press F9, and you’ll get the answer right there in the Formula bar:

Now, if you add to that formula…

…and then press F9, you’ll get:

As you can see, you can build a formula in the Formula bar and see the results as you proceed.