Ever hear impossibly-large numbers quoted as the odds against a cell or a particular DNA molecule having formed “by accident” to create the first living thing? It’s an example of the propensity of creationists to entirely miss the point and set up a specious straw man, ripe for destruction.
Ronald Stearns suggests the following to help them see where they are missing the point:
One demonstration that has worked well for me in illustrating the difference between a priori and a posteriori calculations just uses a deck of cards. Give someone a deck of cards, ask him to shuffle it, and then read off the first 26 cards. After your subject does that, jump at him and question his veracity. “You don’t really expect me to believe that sequence is what you pulled up, is it? The odds against getting exactly that sequence is 2 x 10 41-to-1 against!” Then, of course, explain that what the odds were before the exercise is irrelevant, because what is important is that SOME sequence occurred, and that the idea is to understand what that sequence actually was, not what the chances were of obtaining that sequence. If your subject has kept the stack of cards intact, then you can show that you have the evidence. It also looks a lot like a set of geological strata, and you can show that it remains valid even if you take the stack and slide it around, twist it, and fold it a bit, [to provide an analogy for how] geologists really can still unlock the story of geological history, with a lot of work.
http://skepticreport.com/sr/?p=499#cards