1, add two numbers with the same sign, take the same sign, and add the absolute values: when the signs of the two numbers are the same, the sign of the addition result is the same with them, and the absolute value is equal to the sum of the absolute values of the two numbers. For example, if we add two positive numbers, the result is still positive, and the absolute value is equal to the sum of the absolute values of the two positive numbers. Similarly, when two negative numbers are added, the result is still negative, and the absolute value is equal to the sum of the absolute values of the two negative numbers.
2. When two numbers with different absolute values are added, take the sign of the addend of the number with larger absolute values, and subtract the number with smaller absolute values from the number with larger absolute values: when the signs of the two numbers are different, the sign of the addition result takes the sign of the number with larger absolute values, and the absolute value is equal to the number with larger absolute values minus the number with smaller absolute values. For example, if we add a positive number and a negative number, the sign of the result depends on the number with larger absolute value, and the absolute value is equal to the number with larger absolute value minus the number with smaller absolute value.
3. Two opposite numbers add up to 0: Two opposite numbers mean that the values are equal, but the signs are opposite. When these two numbers are added, their sum is 0. For example, when we add a positive number to its reciprocal, the result will be 0. This is because their absolute values are equal, but their signs are opposite.
4. When a number adds 0, it still gets the number: when a number adds 0, the result is still the number itself. Whether this number is positive, negative or 0, the result of adding 0 will be equal to this number.
The importance of learning mathematics
Mathematics has cultivated our logical thinking and analytical ability. Solving mathematical problems requires logical reasoning, induction and deduction. These thinking methods are not only useful in the field of mathematics, but also can be applied to other disciplines and real life. Mathematics teaches us to solve problems by analyzing problems, building models, finding solutions and verifying answers. This problem-solving ability is very important in school and career, and it is necessary to solve mathematical problems.
Many concepts and proofs in mathematics need creative ways of thinking. Learning mathematics can cultivate our creativity and imagination, and help us discover and put forward new solutions, theorems and theories. Mathematics is the foundation of many disciplines. In the field of natural science, mathematics is an important tool to help us understand and study natural phenomena in physics, chemistry, biology and other disciplines. In engineering technology, mathematics supports engineering calculation, data analysis and modeling.