# Excel: filling a table based on trendline equation without creating a chart/trendline

Is it possible to generate a trendline equation without drawing a graph?

I have a column that is missing about 30 data points, I'd like to fill the blanks based on a trendline of the existing data

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## 1 Answer

Excel's functions "FOR3ECAST" or "TREND" (using array-formulae) will get you what you want assuming the trend is linear.

By futzing with the data, you may be able to get a polynomial curve fitting .

This taken from Excel Help:

FORECAST

FORECAST(x,known_y's,known_x's)

Calculates, or predicts, a future value by using existing values. The predicted value is a y-value for a given x-value. The known values are existing x-values and y-values, and the new value is predicted by using linear regression. You can use this function to predict future sales, inventory requirements, or consumer trends.

TREND

TREND(known_y's,known_x's,new_x's,const)

*Returns values along a linear trend. Fits a straight line (using the method of least squares) to the arrays known_y's and known_x's. Returns the y-values along that line for the array of new_x's that you specify.*

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Any way to calculate the missing values if the trend is not linear? – clabacchio Nov 28 '13 at 14:32