One of the most powerful uses for charts in Excel is to show how two values compare to each other. But what if those values aren't measured in the same way -- for instance, you want to show the dollar value of widget sales in each of 3 years and the percentage of overall corporate sales for which widgets account in each of those three years. How do you do this in Excel?

1. Make a new chart object
2. Create a new series in the chart
3. Populate that series with the data with the smaller range (otherwise you may not be able to see the data to manipulate their display)
4. Format the data as you prefer
5. Create a new series in the chart
6. Populate that series with the data with the larger range
7. Right-click on the new data and select "Chart Type"
8. Format the new data as you prefer
9. Right-click on the new data and select "Format Data Series"
10. Click on "Axis", then, if necessary, ensure that you plot the series on the "Secondary Access"

Unfortunately, unless you're very lucky in your data, you won't get two axes that share a zero line, but that's not always a major problem. If you're determined, right-click on the axis, select "Format Axis", click the "Scale" tab, and play with it some.