Oh, almost forgot! (can't edit so I'll reply to myself) - there's no way for you to set a fixed seed using the built in random number generator. REALLY hope you don't need to reproduce your results because it's essentially impossible. Again, it's technically possible to implement your own Lehmer random number generator within Excel and rely on that and again VBA is always and option, but let's be realistic. The people who understand the need for setting fixed seeds, can implement their own random number generator, and/or are comfortable actually programming aren't going to using Excel anyway (willfully at least)