1. Observe the laws and master the changes: when filling in the addition and subtraction operations, you should first observe the laws and changes in the questions. For example, if you fill in1-2+3-4+5-6-7+8-9+10, you can find that every two numbers are a group, the former number is positive and the latter number is negative, and the sum of each group is-1. So according to this rule, you can fill in+1, -2, -3, -4, +5, -6, -7, +8, -9 and+10.
2. Determine the symbol, and then fill in the number: when filling in the addition and subtraction operation, determine the symbol of each number, that is, the symbol. There is a positive sign in front, followed by a negative sign, and vice versa. For example, when filling in 9+8-7-6+5-4-3+2- 1, you can first determine the symbol, that is, the first two numbers are positive, followed by negative numbers, until the last number 1 is negative. So you can fill in +9, -8, -7, -6, +5, -4, -3, +2,-1 in turn.
3, appropriate split, simplify the complex: when filling in the addition and subtraction operations, if the topic is more complicated, you can properly split and simplify the complex. For example, when filling in 1+2+3+4+5+6+7+8+9, it can be divided into two parts, that is, 1 to 4 is a part and 5 to 9 is a part. First calculate the sum of the two parts, and then add them to get the final result.
Application of addition and subtraction in landscape architecture;
1, Math Contest: In Math Contest, the problems of addition and subtraction often appear. These questions usually give some numbers and symbols for students to fill in the results of addition and subtraction. By mastering the skills of addition and subtraction, students can answer such questions more quickly and accurately, and improve their competition results.
2. Formula puzzle: In the formula puzzle, some numbers and symbols are usually given for students to fill in the results of addition and subtraction. But there are usually some numbers or symbols in the questions, which require students to complete the formula through reasoning and thinking. By mastering the skills of addition and subtraction, students can solve such problems more easily and improve their thinking ability and problem-solving ability.
3. Daily life: In daily life, addition and subtraction operations are also widely used. For example, when shopping in a supermarket, you need to calculate the price and preferential amount of the goods; When calculating wages and expenses, you need to calculate the results of addition and subtraction. By mastering the skills of addition and subtraction, these calculations can be completed more quickly and accurately, and the errors and losses caused by calculation errors can be avoided.