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“商的变化规律”是“除数是两位数的除法”中的一个重要知识,同学们要是能够熟练掌握,灵活应用,不但可以使一些计算简便,提高计算速度,还可以从中感受到学习的乐趣和数学的魅力。规律一:被除数和除数同时乘或除以相同的数(0除外),商不变。典型例题:计算:165÷15 9100÷70思路分析:计算“165÷15”时,可以把被除数和除数同时乘以2,然后再除,以便简算;对于“9100÷70”的计算,可以把被除数和除数同时除以10,使计算简便。
“The law of business ” is an important knowledge in “divisor is a two digit division ”, if students can master and flexible application, not only can make some calculations, improve calculation speed, but also from which Feel the joy of learning and the charm of mathematics. Rule 1: dividend and divisor multiply or divide by the same number (except 0), the same business. Typical example: Calculation: 165 ÷ 15 9100 ÷ 70 Analysis of ideas: Calculation of “165 ÷ 15”, the dividend and divisor can be multiplied by 2 at the same time, and then divided in order to make the simple calculation; for the “9100 ÷ 70 ” The divisor and the divisor can be divided by 10 at the same time, making the calculation easy.