This number 105263157894736842www.ddhw.com has an interesting property: multiplying it by any of 2,3,4,5,6,7,8,9 gets a such repeating number. However, of course, not by 10. My method: Let x be the old number, y be the last diget, then (x-y)/10+y*10^n=2x we got x =(99...9/19)*y =52631578947368421*y (instead of multiplication we can use division which I think easier) www.ddhw.com Since the first diget must be less than 5 (otherwise it multiplied by 5 will be more diget), y not= 1 when y=2, we have x= 105263157894736842 when y=3, we have 157894736842105263 when y=4... look like all the results for x are such repeating numbers.
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哈哈哈哈 O(∩_∩)O哈哈~ 好久不来了，不小心看了一眼自己主页，发现自动关联了自己以往发过的帖，点进这个看了一眼，笑个半死。。。敢情我当初还发过这么搞笑的东西啊，我自己完全不记得了 
雷达卡
发表于 2005-3-15 18:20:42