Addition and subtraction means adding two numbers with the same symbol, taking the same symbol and adding their absolute values. Add two numbers with different signs, take the sign of the number with larger absolute value, and subtract the number with larger absolute value from the number with smaller absolute value. Subtract two numbers with different signs, a negative number is a positive number, and zero plus or minus any number equals the original number.

Definition of positive and negative numbers

Negative number is a mathematical term. Numbers less than 0 are called negative numbers, and negative numbers and positive numbers represent quantities with opposite meanings. Negative numbers are marked with a negative sign, which is equivalent to the negative sign "-"and a positive number, such as 2, which represents the opposite of 2. Therefore, any positive number with a negative sign becomes a negative number, which is the antonym of its absolute value.

On the number axis, negative numbers are all on the left of 0, and the earliest record of negative numbers is China's ancient mathematical work "Nine Chapters Arithmetic". In the calculation, it is stipulated that "positive calculation is red and negative calculation is black", that is, red calculation is used to represent positive numbers and black is used to represent negative numbers. Two negative numbers are relatively large, and the absolute value is large but small.

Positive number is a mathematical term. Numbers greater than 0 are called positive numbers, and 0 itself is not a positive number. Positive numbers and negative numbers represent quantities with opposite meanings. Positive numbers are usually preceded by a "+"symbol, which can usually be omitted. On the number axis, all positive numbers are on the right of 0.