关键词为 “数字” 的文章
6174 初看一点也不起眼,也许你会问它有什么神秘的呢?
我们先进行一番计算,选择一个4位数,每位上的数都不能相同(也就是不能是1111,2222,3333,4444..),
例如选择2009(今年年份),先对这个数上的每位数字重新洗一下,得到最大的数是9200,最小的数是0029,两者相减,对结果再按照上述规则继续下去
9200— 0029=9171
9711—1179= 8532
8532—2358= 6174
7641—1467= 6174
………
现在我们再随机选一个数:比如1234,那么
4321—1234 =3087
8730—0378= 8352
后面就不用再算了。6174这个数就是印度数学家Dattaraya Ramchandra Kaprekar发现的Kaprekar常数——任何4位数,你都可以在7步内计算得到6174(如果没得到,肯定算错了;-))。
其它位数有的也有相应的Kaprekar常数
sfufoet 在煎蛋厨房里提到这个网页:What’s Special About This Number?
0 is the additive identity.
1 is the multiplicative identity.
2 is the only even prime.3 is the number of spatial dimensions we live in.
4 is the smallest number of colors sufficient to color all planar maps.
5 is the number of Platonic solids.
6 is the smallest perfect number.7 is the smallest number of faces of a regular polygon that is not constructible by straightedge and compass.
8 is the largest cube in the Fibonacci sequence.
9 is the maximum number of cubes that are needed to sum to any positive integer.10 is the base of our number system.
⋯⋯
是不是比较拽?