We put ourself in the poor situation, we need money, lets say about 100 000 Euro, and[br]we haven't any other opportunity, except borrowing it. In the real world there are many[br]different types of loans. Before putting the signature on the right place of the contract,[br]we have to choose one credit. Which one will fit perfectly? It's obvious, everybody tries[br]to get the best credit! Such a scenario allows many mathematical questions on different[br]intellectual levels, from school to research. Again, the article's focus is on secondary[br]education. We deduce the problem: "Which credit is the best?"