Mighty Gorgons

I explained it correctly (although I've never needed advanced mathematics in my life – everything could be solved at a simpler level). But it's better (easier) to use a table. Moreover, there are also upper limits, and chance is not a guarantee, no matter how much you calculate it. With a table, you don't need to memorize the whole thing, just the principle of its construction – and you don't have to worry. It's like the Lord's Prayer.