How to set default values on the input table?

I have an input form with three input columns. The first needs to have a predefined amount in it (cannot be changed by user), the second is a quantity to be entered by the user, and the third is a calculation using the first two fields. Can you help me with this?

https://www.jotform.com/build/91576816100152

I can see a similar question has been asked before, please kindly note that it's not possible to set a default value to the input table fields through the settings, but alternatively you may do this following the workaround my colleague explained here: https://www.jotform.com/answers/1691366

Also, besides using the input table you may try using the Spreadsheet widget, you can find it here: https://widgets.jotform.com/widget/spreadsheet

This guide will help you adding the widget to your form: https://www.jotform.com/help/252-How-to-Add-a-Widget-to-Your-Form

On the widget settings you will find how to configure the widget: 

Thanks.