Need auto populated field based on some calculations.

I am having a numeric field now what I need is when somebody add any number in the field, form automatically divides it by 5 then whatever the answer is equal number of fields will appear automatically. If possible.

If I understood you correctly the user will enter a number inside of the field and you want to divide that number by 5 and show the same number of fields the result is equal to. Is that correct?

First, you will have to perform a calculation inside of the form and I would suggest you to round the result. 

How to Perform Form Calculation Using a Widget

Form Calculation - Math Function Reference

Most likely you will also have to set the max value of the number field to prevent users to enter a number that is greater than a possible number of fields. 

You can show the fields with the conditional logic. 

How to Show or Hide Fields Base on User's Answer

Hide or Show Multiple Fields at Once

Here is my demo form: https://form.jotform.com/80594639822972 

Feel free to test it and clone it. 

If I did not understand your question correctly, please explain in more details what are you trying to archive and provide us a link of a form you are working on.