1, rounding is an accurate counting reservation method. When taking decimal approximation, if the highest digit of mantissa is 4 or less, the mantissa is removed. If the highest digit of mantissa is 5 or more, the mantissa is rounded and "1" is input before it, which is called rounding method.

2. It is required to find the approximate decimal places by rounding, when to use four rooms and when to use five rooms, which are all places that everyone pays more attention to; Secondly, we should understand the matching relationship between the number of digits reserved by decimal and the number of digits accurate to decimal part; The more digits reserved for understanding decimals, the higher the accuracy, and the zero at the end of decimals cannot be removed when seeking approximate values.

3, rounding is a simple method, the basic intention is to take a midpoint, less than the midpoint for small back, greater than the midpoint for big back. However, because the traditional calculation is manual, the accuracy used is limited, and the rounding is not without bias: 1, 2,3,4 has only four points, while 5,6,7,8,9 has five points.

Therefore, there is a law of "four families and six entrants". With a computer, single-precision floating point has about 7 digits (decimal), and double-precision floating point has about 15 digits, so the problem of how to do five is not often considered.

Mathematics learning method

Mathematics learning methods include the following aspects: first, we should master the basis of mathematics learning, that is, basic concepts, laws and methods. Secondly, after you finish the topic, you should sum it up carefully, so that you won't spend too much time and energy when you encounter similar problems in the future.

Third, we should have a comprehensive understanding of mathematical concepts, and we should not generalize by partiality. Fourth, the ultimate goal of learning concepts is to use concepts to solve specific problems, so we should actively use the learned mathematical concepts to analyze and solve related mathematical problems. Fifth, we should master the problem-solving methods of various types of questions, sum them up consciously in practice, and gradually cultivate the analytical habits that suit us.

Sixth, we should actively improve the ability of comprehensive analysis of problems and analyze them with the help of text reading. In addition, we should have good psychological quality and strong interest in learning, strengthen reflection, read notes carefully, and read the textbook content and the class notes of the day before doing homework.