Please Note: This article is written for users of the following Microsoft Excel versions: 97, 2000, 2002, and 2003. If you are using a later version (Excel 2007 or later), this tip may not work for you. For a version of this tip written specifically for later versions of Excel, click here: Reading Values from Graphs.

When creating charts from Excel data, you can smooth out the lines between data points by using any number of methods. At some point, you may want to actually figure out how Excel does its calculations to determine where to actually plot points along the line. Rather than visually trying to figure out where a point falls, you can follow these steps:

1. Right-click on the data series in question. Excel displays a Context menu.
2. Choose the Add Trendline option from the Context menu. Excel displays the Add Trendline dialog box. (See Figure 1.)
3. Figure 1. The Add Trendline dialog box.

4. Make sure the regression type you want to use is selected.
5. Display the Options tab.
6. Make sure the Display Equation on Chart check box is selected.
7. Click on OK.

The result is that Excel shows a formula, on the chart, that represents how it calculated each point along the line. You can then use this formula to determine points, as well. No more guessing! Once you know the formula, you can turn off the formula display if you want it off.

If you would like to know the different formulas that Excel uses for different types of trend lines, you can use the online Help system to search for "equations for calculating trendlines."

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (3247) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Reading Values from Graphs.

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Michael (Micky) Avidan    31 Mar 2016, 09:53
@Tamar,
3E-05x = 0.00003x
The carret (^) means: "to the power of".
For instance: 2^4 = 2*2*2*2
--------------------------
Michael (Micky) Avidan
“Microsoft® Answers" - Wiki author & Forums Moderator
“Microsoft®” MVP – Excel (2009-2016)
ISRAEL

Tamar    30 Mar 2016, 20:05
Hi there,
I made a graph on excel, but can't interpret the formula it gave for me for the trend line (Which is polynomial 3).

y = 3E-05x^3 - 0.1947x^2 + 391.12x - 261965

What is that in standard notation?
Specifically for what the 3E-05 means.

Thanks

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