Aligned with the educational and framework plans of the states as well as the KMK educational standards, the new world of numbers has been developed in intensive collaboration with teachers who have implemented and further developed the concept of holistic mathematics instruction. General mathematical competencies such as problem-solving, reasoning, and communication are specifically cultivated. Review exercises and essential knowledge, along with daily practice in the workbook, ensure the necessary foundational skills. The topic area of data and chance is considered from the very beginning. A systematic course in practical arithmetic and authentic, increasingly open real-life situations aid in understanding the environment. The course offers suggestions for joint teaching phases and individual follow-up work, even in mixed-age classes. All tasks are labeled accordingly.