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# How to make a double reciprocal in Excel

Updated April 17, 2017

When you multiply a number by its reciprocal you get 1. Therefore, to find a reciprocal you should divide 1 by that number. The reciprocal of 2 is ½ and 2 x ½ = 1. A Lineweaver-Burke plot is also known as a double reciprocal plot because the two values on the axes of the plot are the reciprocals of the original data. You can set up a Lineweaver-Burke plot in Excel by calculating the reciprocals of your data set. The source data needs to be in the form of two columns of values.

Open Excel with a new worksheet. Put titles in A1 and B1 for the two columns of your source data.

Split your pairs of data into two columns. Write the series of each coordinate in each column. Add one more pair of (0, 0) at the bottom of the data.

Click in A2 and drag a frame around the two columns of data. Click on the Data ribbon and press the “Sort” button. This will bring up a dialogue box.

Select the name of your first column for the “Sort by” value. Order from smallest to largest and check the “My data has headers” box. Press the “OK” button to close the Sort box.

Click in A1 and drag a frame around it and B1. Press “Control” and “C” to copy the values. Click in C1 and Press “Control and “P” to paste the two headings. Click in C1 and insert “1/” in front of the title. Do the same in D1.

Enter 0 in C2 and D2. Type =1/A3 in C3. Press the “Enter” key. Click in C3 to get a frame around it. Click the small square in the bottom right corner of the frame and drag the frame across to D3. Click on the square again and drag the frame down to the limit of your original data columns. While the data is still framed, press the right button on the mouse. Select “Format Cells” from the right-click menu. Specify “Number” and three decimal places. Press the “OK” button.

Draw a frame around the two reciprocal data columns, including the 0, 0 values in the first line. Go to the Insert ribbon and select “Scatter” in the “Charts” section. Select the first format in the scatter plot list. This will generate a double reciprocal plot for your data.