This is question is about binary. As someone said it previously, it is about 2 to the power of something. So if they say no, then it is 0 They said yes then it means it has got that power ( power=order).
So for example, if you are raising the first card and then people say yes but the no to the other cards, that mean 2^1 is yes and it means the person is thinking 2 in their mind. I hope this helps.