A. multiply; is　　    B. multiply by; is    C. multiply; are　　  D. multiply by; are

Now boys and girls，let’s begin our class．As I know, you are interested in some strange math problems．So today I’m going to tell you one of the strangest ways to multiply numbers of two or more figures．Maybe you don’t know the word “multiply”．The word “multiply” mean s“乘．．．，乘法的乘”in Chinese．For example，8 multiplied by 2 is l6．It means “8乘以2是16” in Chinese．Do you understand now? Of course．there are many ways to multiply numbers．But here is one of the strangest．

Imagine you wish to multiply 23 by 17．In Chinese，it means 23乘以17．Half of 23 is 11．5．Write only 11 under 23 as you see in the paper．Half of 11 is 5．5．Write only 5 under 11．Now think it over, what number will you write under 5? Yes, you are right, just 2．Now please write the number under 5．Continue until you have 1．

Now write numbers under 17．But this time you must multiply each number by two to write the number under it．For example, you should write 34 under 17．As a rule, what number will you write under 34? Yes, you are right, 68．Now please write the number under 34．Continue until you have a number on the same line as 1．Now draw a line through any row that has an even number on the left．Yes, even number means 偶数 in Chinese．In our example there is only one even number．Right? Now please draw a line through the line that has au even number on the left．Now add the rest of the numbers in the right hand row．Believe it or not, you will get the right answer．What is it? OK．Please write the number, I mean the right answer in the right place．

Now class, I'll give you several minutes to discuss how it works．

1．What is the speaker most probably doing now?

A．Giving a lesson．                        B．Holding a meeting．

C．Having a party．                         D．Playing a game．

2．What number does the speaker tell you to write under 5?

A．2．                B．5．5．            C．11．              D．10．

3．What is the last number you should write?

A．68．            B．272．             C．391．             D．255．

4．Which subject is the speaker teaching?

A．Chinese．          B．Chemistry．        C．Math．            D．Science．

5．What does the speaker tell you to do at the end of the talk?

A．To have a rest．                         B．To do homework．

C．To have a discussion．                    D．To play a game．

It’s possible to do many simple tricks with numbers. Here is one trick, if you follow the instructions, you will find it’s really interesting.
First, write down your house number. For example, if your address is 73 Jin Shang Road, you would write down 73. After you write down your house address number, you double it. Then add 5 to this doubled number. For example, if your address is 73 and you double it, you will get 146. Then you add 5, you will get 151.
And then, multiply this number by 50. In our example here, you’ll get 7550. The next step is to add your age to this total. For example, if you’re 16 years old, you should add 16 to this total. In our example here, the result will be 7566.
After that, you have to add the number of days in a year, which is 365. In our example here, 365 added to 7566 is 7931.
The final step is this: Subtract 615 from the number that you have. Take away 615 from the total. In our example, 7931 minus 615 is 7316.
The result here—7316—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 16 is the age that we used.
Isn’t it interesting? Do you want to have a try now?
【小题1】How many steps are there in the trick?
A. Four                          B. Seven                    C. Nine
【小题2】The third step is ______.     
A. ＋5                           B. ×50                          C.－615
【小题3】Tom is 38, he lives in 89 Jin Shang Road. If he plays this trick, he will get______ in the end.
A. 3889                         B. 9150                          C. 8938
【小题4】When you play this trick, ______ is Not the number you have to use every time.
A. 50                          B.73                        C. 365  
【小题5】The best title of this passage is “______”.    
A. A trick with numbers          B. An interesting problem        C. How to work out a trick