Required Mathematical Intelligence

Chapter 136 The Age of Mathematician Wiener

Chapter 136 The Age of Mathematician Wiener
我今年岁数的立方是个四位数,岁数的四次方是个六位数,这两个数,刚好把十个数字0、1、2、3、4、5、6、7、8、9全都用上了,维纳的年龄是多少?

[Answer: At first glance, this question is difficult, but it is not.Suppose Wiener's age is x, firstly the cube of age is four digits, which defines a range.

10的立方是1000,20的立方是8000,21的立方是9261,是四位数;22的立方是10648;所以10=<x<=21x四次方是个六位数,10的四次方是10000,离六位数差远啦。

15的四次方是50625还不是六位数,17的四次方是83521也不是六位数。18的四次方是104976是六位数。20的四次方是160000;21的四次方是194481.
综合上述,得18=<x<=21,那只可能是18,19,20,21四个数中的一个数;因为这两个数刚好把十个数字0、1、2、3、4、5、6、7、8、9全都用上了,四位数和六位数正好用了十个数字,所以四位数和六位数中没有重复数字。

Now let's verify one by one, the cube of 20 is 80000, there are repetitions; the fourth power of 21 is 194481, there are also repetitions; the fourth power of 19 is 130321; there are also repetitions; the cube of 18 is 5832, and the fourth power of 18 is 104976 , are not repeated.Therefore, Weiner's age should be 18. ]
(End of this chapter)

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