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做几次简单运算,可以发现一个小小规律。任意写一个三位数,例如135。把它的数字倒过来写,成为531。用其中较大的减去较小的,得到:531-135=396。换几个另外的三位数,也做同样的计算,分别得到:876-678=198,995-599=396,963-369=594。以上4个式子里得到的差,有一个明显的共同点:差的中间一位数字都是9。再仔细看看,还发现一个共同点:差的首、尾两个数字的和等于9。这样,通过观察和归纳,就发现了三位数颠倒相减的规律。还可以再随意写很多三位数颠倒相减的例子,来验证上面得到的规律,结果大部分都完全符合,只有两种
Do a few simple calculations, you can find a small law. Write a three digit arbitrary, for example 135. Write its number upside down and become 531. Use the larger of them to subtract the smaller one, resulting in: 531-135 = 396. For a few additional three-digit numbers, do the same calculations, respectively: 876-678 = 198,995-599 = 396,963-369 = 594. The difference between the above four formulas has one obvious thing in common: one in the middle of the difference is nine. Take a closer look and find one thing in common: the sum of the first two digits is equal to nine. In this way, through the observation and induction, we found that the law of the three-digit inversion subtraction. You can also random write a lot of three-digit inverted subtraction example to verify the law obtained above, most of the results are fully consistent, only two