Generally, the method of rounding is used to estimate two digits into integer ten digits, three digits into integer hundred digits, and one digit remains unchanged, and then add, subtract, multiply and divide. The estimation methods can be diversified, including one-step method, mantissa method, compromise method and so on.
Sometimes it depends on the specific topic. For example, 192÷6 can be estimated by multiplication formula. Take 192 as 180, and then calculate 180 ÷ 6 = 30 to get 192÷6≈30.
In primary school mathematics teaching, estimation is paid more and more attention by teachers and students, and it is favored even more in the big teaching environment of advocating "useful mathematics".
Strengthening students' estimation consciousness and letting primary school students master some simple estimation methods is of positive significance to help students learn to use mathematical thinking mode to observe and analyze the real society, solve problems in daily life, and thus cultivate their sense of numbers and sense of mathematical application.
Extended data:
Example 1: For example, π is rounded, leaving 3. 14. But sometimes you can use "one-in method" and "one-out method" instead of rounding. The rounded fourth house is 1, 2, 3, 4 and the fifth house is: 5, 6, 7, 8, 9. For example, 288 students have a spring outing, and 45 people have a bus, which is 6.4 buses. However, you must get into a bus to avoid letting more people out and fewer cars. Because the number of cars cannot be decimal, seven buses are needed.
For another example, 10 16 liters of gasoline, if you want to refuel a car, you can add 50.8 cars on average to 20 liters, but you must remove the tail to let more cars come out and less fuel. Because the number of cars cannot be decimal, only 50 cars can be refueled.
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