Calculate where in the course you are

Good day everyone. A client has asked to add a progress bar in the slide master to show how far into the course the learner is. I thought it would be easy, just add the Progress Through Project variable. The client indicated that when you went forward in the project, it works great; however, if you use the Prev button, the percentage stays. I said it's because Storyline remembers how far the learner has gone. She said she wanted the progress bar to show the percentage for that slide, even if the learner went back. So for example in a 10 slide course. With the Progress Through Project variable if I went to slide 5, it would read 50%. If I went back to slide 4, it would still read 50%. The client would like the following experience. They got o slide 5, they get 50%, if they use Prev and got to slide 4, it would read 40% not 50%.

Is there an elegant way to do this? I tried calculating  the variables Project.SlideNumber/Project.TotalSlides, but this gave me a 2 decimal result that the client does not want. She would like a whole number (43% vs 42.56%).

Thank you!!