Renate Motzer introduces the world of fractions and connects them with decimal numbers. She clearly demonstrates that fractions can be understood as parts of a whole, but also as ratios of two quantities. The author explains in an understandable way why roots cannot be precisely expressed as fractions, how to find good approximations, and why an unusual addition of fractions can lead to paradoxical results. Furthermore, she practically explains the application of fractions in percentage calculations and probability theory, and finally discusses various methods for calculating averages.