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为了提高计算的正确率,可以用估算作为检验校核的第一步,同时在这种实践活动中培养学生估算的习惯和能力。这里介绍几种常用的估算方法。一、取整法将运算数据取整数或整十、整百、整千数进行估算。例1.4048÷8=56 估算:4048÷8≈4000÷8=500,可见56是错误的。例2,42.12÷5.85×1.5=7.2×1.5=108 估算:42.12÷5.85×1.5≈42÷6×2=14 可见原答案108错误。例3.0.7÷0.035=200 估算:0.7÷0.035=0.700÷0.035=700÷35=20
In order to improve the accuracy of the calculation, we can use the estimation as the first step of the verification and verification, and at the same time cultivate the students' estimated habits and abilities in such practical activities. Here are a few commonly used estimation methods. First, the rounding method will calculate the data to take an integer or whole ten, the whole hundred, the whole thousands of estimates. Example 1.4048 ÷ 8 = 56 Estimate: 4048 ÷ 8 ≈ 4000 ÷ 8 = 500, we can see that 56 is wrong. Example 2,42.12 ÷ 5.85 × 1.5 = 7.2 × 1.5 = 108 Estimate: 42.12 ÷ 5.85 × 1.5 ≈ 42 ÷ 6 × 2 = 14 We can see that the original answer 108 is wrong. Example 3.0.7 ÷ 0.035 = 200 Estimate: 0.7 ÷ 0.035 = 0.700 ÷ 0.035 = 700 ÷ 35 = 20