Regra de 3 is a free Android application developed by Matheus Piscioneri that provides a practical way to solve problems involving four values, of which we know three of them. This simple rule of three idea is commonly used in many everyday situations, and the app uses a four-step process to solve them.

The first step is to build a table, grouping the quantities in columns and linking each value to its greatness. The second step is to identify whether the magnitudes are directly or inversely proportional, which the user will see after the last step. The third step is to assemble the equation by multiplying the values in the form of X if the quantities are directly proportional. Finally, the fourth step is to solve the equation.

Regra de 3 is an easy-to-use application that provides an essential tool for anyone who needs to solve everyday problems quickly. It is a perfect fit for students, professionals, and anyone who wants to solve problems with ease.