How do I perform calculations and display results within a matrix field?

How do I multiply the value of column 1 and column 2 and show the result value in the column 3 of the matrix table?

Thanks.

If you want to perform calculations directly within a matrix, such as you would in an Excel spreadsheet, you will have to use our Spreadsheet widget instead of the Matrix field:

https://www.jotform.com/help/252-How-to-Add-a-Widget-to-your-Form

The Spreadsheet widget can perform calculations similar to those of traditional Excel spreadsheets or Google Spreadsheets:

Upon adding the Spreadsheet widget to your form, please add your desired calculations as "Default values" of the widget. If you need any further assistance in setting up the conditions, please let us know and we will be happy to help.