According to the Pareto principle, when it comes to many outcomes, 80% of consequences come from 20% of causes. In other words, 80% of your effort gives you 20% of your results (and vice versa). For example, if you’re preparing for an exam, rather focus on studying and revising your main topics as opposed to trying to learn something new. This is because about 80% of your exam success will come from the last 20% you spend on studying for the exam. Also, it is possible for you to answer between 80 and 100% of your exam by learning 20% of your study materials.