The estimation methods of the three levels are: the tail-removing method, the one-step method, the four-step method, the ten-step method, and the all-round method.

1. truncation method: that is, the mantissa of each number is removed and the integer is calculated.

For example, Dongfang Travel Service organized several tour groups during the 11th period. The situation is: Lijiang 524, Huangshan 208, Great Wall 602, Jiuzhaigou 365,438+09, Emei Mountain 265,438+09. How many people did the travel agency receive during the eleventh period? Remove the mantissa, and add the whole hundred numbers to get 524+2084602+3104219 ≈ 500+200+600+300 h201800 (person).

2. One method: that is, the highest digit of each number is added with 1, and the integer of ten is taken for calculation. For example: 28+15+7+24 ≈ 30+20+10+30 = 90.

3. Four-shed sealing method: that is, people with mantissa less than or equal to 4 and equal to or greater than 5 go in and take all ten or hundred teachings for calculation. For example, "1.8 Jin of apples, how much should I pay per Jin of 420 yuan"? The estimated value is 42× 1, 8≈4×2=8 (yuan).

4. Ten-point method: Add the related teaching together and get the first addition close to 10. For example:17+8+12424 (17+12)+(8+24) ≈ 30+30 = 60.

5. Solve the whole by parts: divide a large whole into several parts on average, and calculate the integer according to the number of parts. For example, to estimate the number of spectators in the stadium, first divide each stand into several parts, count the number of people in one part, then estimate the educational background of one stand, and finally calculate the number of people in the whole stand according to several spectators.

Auxiliary method

1, establish the wrong title book: this involves the problem of Chinese reading comprehension. Children who read a lot have a good understanding of application problems and can help them build a wrong problem book. At the same time, parents can help their children choose some classic questions that are easy to make mistakes. This ability should be taught to children slowly.

2. Children need to be clear about the learning priorities in the usual classroom: attending classes, following the teacher, and then improving their abilities. Children have no knowledge of mathematics, but they are vague about it in their minds. Parents can help children clear their minds and grow up with their parents.

3. Pay attention to oral arithmetic training and lay a solid foundation for calculation: how to do math estimation in grade three? I think oral arithmetic is a basic skill that students must master skillfully, and it is one of the most basic and important skills in mathematics learning. Oral arithmetic is related to whether you can successfully learn and master a series of contents such as multi-digit addition, subtraction, multiplication and division, decimal and fractional operations.