1、74×( 100—5÷2)。
2、85 ×(95— 1440÷24)。
3、58870÷( 105+20×2)。
4、80400—(4300+870÷ 15)。
5、 1437X27+27X563。
6、8 1432( 13x 52+78)。
7、 125×(33- 1)。
8，37.4 I (8.6+7.24-6.6)。
17、384÷ 12+23×37 1。
18, (39-2 1)×(396÷6).
19、 156×[( 17.7-7.2)÷3]。
20、[37.85-(7.85+6.4)]。
Calculation method of parting:
The main thing to master is to remember to calculate multiplication and division first, and then add and subtract. In the successive calculation of multiplication and division, it should be calculated from left to right. When you encounter parentheses, you must first calculate the inside of parentheses.
In the process of separation, the operation sequence line should be drawn according to the operation sequence, and the "three checks" should be done well. First of all, check whether the numbers and symbols copied from books to exercise books are correct. Second, check whether the numbers and symbols copied from horizontal to vertical are copied correctly. Third, it is necessary to check whether the draft is copied vertically, horizontally, and whether the decimal point position is correct or not.
Methods of learning mathematics well
1. Cultivate interest: Interest is the most important motivation for learning mathematics. Understanding the application and practical significance of mathematics and trying to solve the problems of interest can cultivate interest in mathematics.
2. Establish a solid foundation: Mathematics is a gradually developing discipline and needs to be built on a solid foundation. We must master basic knowledge such as arithmetic operation and algebra in order to better understand and apply more advanced concepts.
3. Do more exercises: Mathematics is a very practical subject, so it is necessary to do more exercises to consolidate what you have learned. Choosing appropriate exercise topics and paying attention to repeated training will help deepen understanding and improve problem-solving skills.