Puzzle tasks not only promote logical thinking and quick mental arithmetic but also guarantee enjoyment in experimenting and developing strategies. With the motivating tasks in this volume, your students will work with the numbers 1 to 9 within the range of 20, playfully training their calculation skills. The number games can initially be solved through trial and error and, with increasing practice, can also be approached strategically. Thanks to the different difficulty levels of the tasks, there is a suitable puzzle for every student – from quick calculators to those for whom practicing and reinforcing is particularly important. To enable children to work independently with the material, there is an option for self-checking. This makes the puzzle tasks perfect for use in independent work, weekly planning, substitute teaching, or simply as a break activity.