While The Bore Factor's description isn't far off the reality you'll be facing as a strategy consultant, for the assessment centre you're likely to get away with just 4-6 slides. Are you allowed to use PowerPoint? When I did my presentation a few years ago, we had to use an overhead projector, so the slides were very brief and to the point. I remember I had 4 slides summarising the key points (Context/History, Problem, Possible solutions, Recommendation/Conclusion), plus one "data" slide to support my recommendation. This was just a simple plot of the key numbers involved, but conveyed the point with great clarity. This seemed to impress the partner enough to result in a job offer. You can't argue with data!