How can I take number responses from several questions and add those in a later statement?

Thank you for your response, @Liz ! I did see that article, however it didn't seem to apply to my situation. I believe that this is explaining how it can recall if I was the one to input values (such as pizza prices).  In my case, however, the person filling out the form would be inputting the numbers. The person may indicate to me that they take 20 minutes to grocery shop, or they may say it is 2 hours. I would want their responses, number answers, to be added up later in the form. Is there a way to accomplish this?

I’m sorry, I may not be describing this well enough. What I am seeing in that video and article is that you can create different values in multiple choice or by using the Number field. However, I am not inputting values. Instead I am asking them open ended questions so that I am not swaying them to say something that is untrue or fitting them into a box.

Instead I am asking questions with the answer field being small text. This way they can tell me exactly how long it takes them to complete tasks. Then can respond as they wish: 1 hour, 20 minutes, 3.5 seconds, whatever it may be. Therefore, I need a solution that is not mentioned in that article or video. I could perhaps tell them to tell me how long in minutes, or in hours (30 minutes, 90 minutes… or 0.5 hrs, 1.5hrs etc) but I still would need their short text response to be added up. 

Is there a way to do that @Liz ?

Hmm, ok- I will give it a try! Thank you!