How can I make the form calculation unchangeable to the public

I am using a form calculation at the end my my survey. However, once the viewer takes the survey, he/she has a chance to change the value of the calculation before submitting. For example, if at the end of the survey(last question) the calculation scores a total of 30 points (from the values assigned to each answer), the viewer can change the value to 40 before submitting. How can i avoid this?

Also, is there a way to make it so that a viewer can submit a survey and only after submission he/she finds out the score (like a quiz)

You will need to set the form calculation field to the read only mode, please see the next animation.

The calculation field seems to be already hidden on your form. You can also show its value on the form Thank You Page by using the field name.

If you need any further assistance, please let us know.