Addition and subtraction within 1000 in 15 minutes a day

The express trainer in mathematics is intended for students in grades 1-4. By practicing for 15 minutes a day, the student will master the skill of solving addition and subtraction problems within 1000 without using a calculator to the point of automaticity. The result of the classes will be not only high grades on tests and exams but also the ability to calculate quickly and accurately in their head.