Equations

  Combinations  

Counting

If you have two experiments, and the first can result in p number of outcomes, and for each outcome, there is a second experiment which can result in q number of outcomes, then the total possible outcomes for the two experiments is p · q.

General counting

If you have x number of experiments, and each experiment can result in h number of outcomes, for example h₁ for the first one, h₂ for the second one, h₃ for the third, etc., then the total number of outcomes for all experiments is \begin{equation} h_{\, tot} = h_1 \cdot h_2 \cdot h_3 ... \cdot \, h_x \qquad \textnormal{Total number of outcomes in } x \textnormal{ experiments} \end{equation}