| [ Season ] in KIDS 글 쓴 이(By): guest (GUEST) 날 짜 (Date): 1998년02월08일(일) 22시01분51초 ROK 제 목(Title): Re: 당신이 결혼할 나이는? Let n be the number you choose, 1 <= n <= 9. In step 2, you multiply n by 9, then 9n = (10 - 1) n = = 10 (n - 1) + (10 - n) = 10 a + b, where 0 <= a, b <= 9. Then a = n - 1, b = 10 - n. Adding a and b always results in a + b = ( n - 1 ) + (10 - n) = 9. Let x be the number of people you've kissed. Step 4~6 yields 9 * 3 + 5 - x = 32 - x. So, by subtracting the number you answered from 32, the adversary can know x, the number of people you've kissed. |