Rational number addition and subtraction calculating rule

The utility model discloses a rational number addition and subtraction calculating rule. A slide rule (2) of the calculating rule is located between two fixed rules which are an auxiliary rule (1) and a number axis rule (3). One side of the auxiliary rule (1) is provided with addition, and the other side is provided with subtraction. Midpoints of both sides of the number axis rule (3) and the slide rule (2) are provided with the number of "0". Left and right sides of the "0" at the addition side of the slide rule (2) are respectively provided with a plurality of continuous positive integers and negative integers, and numbers opposite to those of the slide rule (2) are disposed on the number axis rule (3). On the subtraction side of the slide rule (2), the left and right sides of the "0" are respectively provided with a plurality of continuous negative integers and positive integers, and the same numbers as those of the slide rule (2) are disposed on the number axis rule (3). The slide rule (2) is drew to vertically align two numbers on the slide rule (2) and the number axis rule (3), and the number, aligned to the "0" on the number axis rule (3), of the slide rule is the result. According to the utility model, students are allowed to easily and quickly understand and use the rational number addition and subtraction calculating rule.