Addition and subtraction algorithm of rational numbers in the first grade of mathematics.

1. Add two numbers with the same sign, take the same sign, and then add the absolute values.

2。 Add two different symbols with different absolute values, take the symbol with the larger absolute value, and subtract the symbol with the smaller absolute value from the larger absolute value. Two opposite numbers add up to 0.

Add a number to 0 and you still get the number.

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