Now, given that I have picked a fair coin, what is the probability that I will get heads twice? So let me write it this way. And this is just notation right here. So the probability of, I'll call it heads, heads, so I get two heads in a row, given that I have a fair coin. It looks like very fancy notation, but it's just like, look, if you knew for a fact that that coin you had is absolutely fair, that it has a 50% chance of coming up heads, what is the probability of getting two heads in a row? Well, then we can just say, well, that's just going to be 50%. So 50% times 50%, which is equal to 25%.