最有趣的数字智力游戏（有解析）

It is possible to do many simple tricks with numbers. Here is one trick. It has seven steps.

First, write down your house number. For example, if your address is 73 Lemon Street, you would write down 73.

Next, double it. In other words, multiply(乘) it by two. Then, add five to this doubled number. For example, if your address was 73 and you doubled it, you would get 146. Then, if you added five, you’d get 151.

Now repeat the first three steps, write down your house number, double it, and add five.

Fourth, multiply this number by 50. In our example here, if you multiply 151 by 50, you’ll get 7550.

The fifth step is to add your age to this total. For example, if you’re 26 years old, you should add 26 to this total. In our example here, the result would be 7550 plus 26, you’ll get 7576.

Sixth, you have to add the number of days in a year, which is 365. In our example here, 365 added to 7576 is 7941.

The seventh and final step is this: subtract(减) 615 from the number that you have. In our example, 7941 minus 615 is 7326.

The result here, 7-3-2-6, is the trick. The first part of the number is the address and the last part of the number is the age of the person. That is, 73 is the address that we started with, and 26 is the age that we used.

If you follow these seven steps with any address and the age of any person. You will get the same result.

Do you want to have a try?

1. according to the trick, what number can you get if you are 16 years old and your house number is 85？

A. 1685                        B. 8516                        C. 8165                        D. 1658

2. How can your age number appear at the last part of the result?

A. It’s really a trick.

B. By taking all the steps except Step1 and Step 2.

C. By taking Step 6and Step 7.

D. By taking all the steps.

3. What’s the secret of the trick?

A. It’s impossible to know.

B. By taking Step 2 and Step 4, we get the formula(公式)：your address number ×2×50.

C. By taking all the steps except 1 and 2, we get the formula: 5×50+your age number+365－615=your age number.

D. Both B and C.

4. Is it possible for us to design another program of getting the same result？

A. No, it’s impossible to find out another way.

B. No problem.

C. I’m not sure.

D. It’s nothing but a trick.

【答案与解析】

1. B。根据文章倒数第3段的The first part of the number is the address and the last part of the number is the age of the person可以得出答案：共有四位数字，前两位是地址的号码，后两位是年龄的数字，所以答案是B。

2. D。只有将步骤全部算完才可以得出答案，因此选D。

3. D。通过选项B的公式可以算出地址号码的100倍，即答案的前两位数字；通过选项C可以算出年龄的数字，也是答案的后两位。将B，C两项加起来就揭开了把戏的秘密，据此可推出答案为D。

4. B。假设某人的address号码为m，其年龄为n，那么根据上面游戏规则，我们可以得出以下公式：(m×2＋5) ×50＋n＋365－615。把该公式展开即可得到：(m×2×50＋5×50＋n＋365－615。通过简单计算我们可以得以下结果：m×100＋n。显然，这个数的千位和百位为address号码，十位和个位为年龄。据此原理，我们可以设计出无数个可以得到同样结果的方案，比如我们可以将游戏中第三步中的加5改为加6，将第七步中减615改为减665，其结果也完全一样的；或者将游戏中第三步中的加5改为加7，将第七步中减615改为减715，其结果也完全一样的；或将游戏中第三步中的加5改为加8，将第七步中减615改为减765，其结果也完全一样的；等等。