Tasks and games with Dienes materials. Children who have explored the number range up to 20 are now ready to discover the world of calculations up to 100. There are many challenges to overcome: the specific pronunciation and writing of two-digit numbers, addition and subtraction up to 100, as well as the new basic operations of multiplication and division. The practical book "Calculation World up to 100" demonstrates how Dienes materials can be effectively used to teach children the new and fundamental calculation methods in a relevant and efficient manner. Not only children who struggle with math benefit from this approach, which allows them to learn and apply mathematical thinking playfully with the help of visual materials. This book provides various strategies and numerous ideas for anyone who cares about the mathematical support of children from the second grade onward.