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判断一个数能否被另一个数整除,最自然的办法就是作除法。但对于一些特殊的数,我们可以研究一些特别的判断方法。小学数学教材中研究了2、5、3的倍数的特征。结论为:(1)个位上是0、2、4、6、8的数,能被2整除;(2)个位上是0、5的数,能被5整除;(3)各个数位上的数字之和能被3整除,这个数就能被3整除。我们先来讨论结论(1)和结论(2),这两个结论可以概括地表达为:个位上的数字能被2或5整除,这个数就能被2或5整除。
Judging whether a number can be divisible by another number, the most natural way is to divide. But for some special numbers, we can study some special judgments. Primary mathematics textbooks studied the characteristics of multiples of 2,5,3. The conclusions are: (1) the number of bits is 0,2,4,6,8, can be divisible by 2; (2) the number of 0,5 on the first place, can be divisible by 5; (3) each digit The sum of the numbers above can be divisible by 3, which can be divided by 3. We first discuss the conclusion (1) and conclusion (2), these two conclusions can be broadly expressed as: a unit of figures can be divisible by 2 or 5, this number can be 2 or 5 divisible.