Need to add a column in cross tab report

Question

This is my cross-tab crystal report for sales per week. In last column I need the "Change" column at last in which ((21-Jun's value - 14-Jun's value)/14-Jun's value)*100 will be shown. But I am not be able to achieve that in crystal report.

**Product                   Customer           31-May       7-Jun       14-Jun      21-Jun**        

J.B. Officeprint 1111       Maxi-Teq            4.00        1.00        1.00        1.00        
                            Microchips          1.00        1.00        0.00        0.00        
                            Parameter           2.00        1.00        0.00        0.00        
                               Total            7.00        3.00        1.00        1.00        
J.B. Officeprint 1420       Maxi-Teq            4.00        1.00        1.00        1.00        
                            Microchips          1.00        1.00        0.00        1.00        
                            Parameter           2.00        1.00        0.00        1.00        
                               Total            7.00        3.00        1.00        3.00        
Motherboard BTX             Maxi-Teq            1.00        0.00        0.00        0.00        
                               Total            1.00        0.00        0.00        0.00        
Motherboard MicroATX        Maxi-Teq            1.00        0.00        0.00        0.00        
                               Total            1.00        0.00        0.00        0.00        
Printer Paper A4            Parameter           0.00        0.00        1.00        0.00        
                               Total            0.00        0.00        1.00        0.00        
Printer Paper A4 White      Maxi-Teq            0.00        0.00        0.00        12.00       
                            Microchips          0.00        0.00        30.00       0.00        
                            Parameter           0.00        0.00        6.00        0.00        
                               Total            0.00        0.00        36.00       12.00       
                 Grand Total                    16.00       6.00        39.00       16.00       

Answer 1

you can do it using calculated member.

go to the preview and right click on 21-June column and go to calculated member and insert column

Edit.................................................................. Go to edit calculation formula and write your code.