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在“两位数除多位数”的学习中,试商要既对又快,关键是方法要灵活,下面给同学们介绍几种试商的高招。高招一:“四舍五入”法。在试商时,除数不是整十数的,我们可以把它看作与它接近的整十数来试商,即除数个位上的数字是4或比4小的就舍去,是5或比5大的数舍去后还要向前一位进一,这样的试商就比较简便。如计算576÷18、672÷42,这两道题里的除数18和42中,18比较接近20,而42却比较接近40,这时我们就利用书本上介绍
In the “double digits in addition to multi-digit ” learning, try to both fast, the key is to be flexible, the following to the students introduce several tactics. Trick 1: “rounding ” method. In the trial, the divisor is not the whole number of ten, we can think of it as an entire number close to it to try quotes, that the number of divisor bits is 4 or less than the 4 homes, is 5 or Larger than the number of 5 to go after the next one, this trial is relatively simple. Such as the calculation of 576 ÷ 18,672 ÷ 42, the two questions in the divisor 18 and 42, 18 is closer to 20, while 42 is closer to 40, then we use the book to introduce