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In everyday life, we constantly have to perform oral calculations, perform actions on numbers (mainly with numbers within 100). The ability to perform arithmetic operations orally develops memory, concentration, attention, thinking and should be developed in every child. The textbook offers a variety of ways to perform oral calculations and exercises to consolidate what has been learnt. The sequence of presentation coincides with the presentation of material in primary school. A large number of drawings clearly demonstrate how easy and fast it is to add and subtract numbers.

The student should complete the tasks independently. The methods of control and verification can be different: checking by adults, checking with a calculator, etc.

The manual will be useful for students, their parents and teachers when teaching a particular topic in mathematics.