Setting up multiple PowerPoint presentations for non IT people to use

Skip this background paragraph if you want to get straight to the question!
Our local Priory has a long and interesting history. It receives maybe 10,000 visitors a year. Occasionally I or a friend give visiting groups, notably members of the USA Sierra Club, a talk before they set off on their UK walk. However most visitors can get this opportunity, so for them we are going to setup a computer display for them. Put simply it comprises a presentation comprising one slide - the menu, and several short presentations using topics from our lecture and other topics. You will have seen displays such as these in museums where you select a topic about which you wish to know more. Problems are that we can't afford touch screen technology, and we have to keep the control simple and prevent fiddling with the technology. A computer which is locked away drives a secondary monitor built into a display cabinet. Only control available to visitor can be either a mouse or a numeric keypad. I would prefer to use the latter but can't get that to work. The mouse option works, but not ideal.

So we have a single slide PowerPoint presentation, M - the Menu - listing Topics 1,2, 3, 4, etc., and several multi-slide presentations - T1, T2, T3, etc. which are embedded in M1. Simple method is to use a mouse and on screen instructions "Click on topic to view". Click on Exit to return to Menu at end.
What I want to do is to number each topic and give the instruction "Select the number of topic required" and automatic return to Menu. But I can't find any way of using a number entry to select an embedded presentation. Is it even possible?

This solution might work for you:

Thanks for taking the time to make a suggestion, but that is how I have done the presentations that work using a mouse. What I am trying to find is a way for a user to select the presentation they want to see by entering a number on a numeric keypad.