1, take the middle number and ignore the decimal point: for the calculation of some large or small numbers, we can take the middle number of these numbers as the estimated value. For example, a set of numbers is10,30,50, and we can take the middle number 30 as an estimate. For some figures after the decimal point, we can ignore them and estimate them. For example, if a number is 2.5, we can estimate it as 2.

2. divisor multiplication: For some formulas that multiply two numbers, we can estimate both numbers as divisors near them to calculate. For example, if a formula is 6.3x3.8, we can estimate 6.3 as 6, 3.8 as 4, and then calculate 6x4=24 as the estimated value.

3. Piecewise estimation: For some large numbers, we can divide them into several segments, and each segment takes the middle number for estimation. For example, if a number is 105, we can divide it into two parts: 100 and 5. 100 Take the median number 10 as the estimated value, and 5 take the median number 3 as the estimated value, and then add them to get the estimated value 13.

Methods of learning mathematics

1, you need to understand the basic concepts and principles of mathematics. This can be achieved by reading more books, doing exercises and listening to lectures. When doing problems, you need to pay attention to the ideas and methods of solving problems, and gradually master these methods.

2. You need to be good at summarizing. Mathematics is a highly systematic subject, and every knowledge point has certain connection. You should learn to summarize the knowledge points, and master their connections, similarities and differences, so as to better understand and use them. You should learn to use calculators, computers and other tools in order to complete calculations more quickly and accurately.

You need to do more exercises. Mathematics is a very practical subject, and only through a lot of practice can we really master mathematical knowledge. Pay attention to the ideas and methods of solving problems when doing problems, and gradually improve your speed and accuracy of solving problems. You need to be good at using tools. Mathematics is a subject that needs a lot of calculation. If you rely solely on manual calculation, it is not only inefficient, but also prone to errors.

You need to develop good study habits. This includes finishing homework on time, listening carefully, thinking positively and so on. Learning mathematics requires patience and perseverance, and only persistent efforts can achieve good results. Learning mathematics needs to pay attention to methods, summarize, do more exercises, use tools and cultivate good study habits. Only by unremitting efforts can we improve our mathematics level.