**Adrian14**How to add interest to calculate?

*This is a re-post of a comment on Form Calculation - Math Function Reference*- JotForm Support Manager
**Jeanette**I have made a demo form for you to see, is this something you are looking for?

- JotForm Support Manager
**Jeanette**If you need further help, please explain in details what is the desired scenario and we will be glad to assist you.

**Adrian14**Thanks, but how to add? I tried, but nothing happened

**jedcadorna**Here's how to add interest to your form calculation.

1. Add dropdown menu that and put your interest value

2. Then add Calculation widget

Your formula should be something like this:

**( loan amount * ( interest / 100 ) + loan amount ) / number of months**This would depends on the name of the fields but basically just follow the formula above.

**Adrian14**Thanks!