Calculating amounts entered in short answer test questions

I am working on a large course consisting of one intro page and four test sections with approximately 100 total questions. Within the test, I have three separate short answer test questions on the same page requiring numeric answers. The answers to these three questions will vary by user, but must always equal 100%. I would like to create an action to calculate the answers provided by the user and only allow them to move to the next test question if the three values provided equal 100%. After much research, I have not been able to figure out a workable solution. Any suggestions are appreciated.