A simple, free educational program supporting the learning of mathematics in the 4th grade of primary school, by Wiesław Salomon, known from several educational programs presented in the vortal. Through several tests included in the program, students can develop the ability to perform basic mathematical calculations (multiplication, division, addition, subtraction) in memory, convert numerical values from the Roman system to Arabic and vice versa, calculate the division of numbers, perform calculations at regular fractions, calculate the field of simple flat figures (in a "grid" system), and translate the verbal notation of numbers into numbers. Mathematics 4 can complement lessons taught in a traditional way, while at the same time relieving the teacher of the burden of teaching simple skills of students.