An "Armstrong number" is an n-digit number that is equal to the sum of the nth powers of its individual digits. For example, 153 is an Armstrong number because it has 3 digits and 13+53+33=153. What is the digit k in the Armstrong number 1,6k4?
2
3
4
5
6
要明白,这里不是6k组成十位,而是1是千位,6是百位,k是十位,4是个位
1^4+6^4+k^4+4^4=1604+10*k (这里最关键的就是把16k4变成1604+10*k )
k(k^3-10)=1604-1553=51,k=3
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