How to calculate total number of particular column (Sum) in visual ?

In the "Maharashtra School Mass Pledge" form, there is column "number of students took pledge". We want to show sum of all entries (total of students took pledge) in the visual report. However, there is no option to show the same.  

Do you mean to say that you wan tot display the sum of the total column you have in form's submission?

Unfortunately it is not possible to display total sum of one fields data and display in submission or visual report. The only possibility is to export the submission in excel and add formula to calculate the sum of the column data.