Solly wants to unlock his friend Koss's combination lock. the lock consists of 4 reels, each reel displays the digits from 1 to 9. Koos tells Solly that the first digit from left to right is a multiple of 3, the second digit is a prime, the third digit is a multiple of 2 and the whole unmber is divisible by 4. By following Koss' clues, waht is the maximum possible number of different ways that Solly can unclock it?
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84927

2007-09-01 20:37
The lock consists of 4 reels...
這個鎖組成4個捲軸
each reel displays the digits from 1 to 9.
每個捲軸有1到9(9個數字)
the first digit from left to right is a multiple of 3
第一位數是3的倍數
the second digit is a prime
第二位數是質數
the third digit is a multiple of 2
第三位數是2的倍數
the whole unmber is divisible by 4.
整個數可被4整除
問題問Solly有多少方法解開它?
第一位數是3的倍數有3.6.9.3種方法
第二位數是基本的有9種
第三位數是2的倍數有2.4.6.8.4種方法
整個數可被4整除
所以第四位數可為4.8.2種
3*9*4*2=216
對嗎?


孫文先

2007-09-02 12:01
翻譯錯誤百出，幾乎無法修正。
Prime是指質數不是基本的，因此答案也是錯的。