Unit 141 Add, Subtract, Multiply, and Divide

B : Hello there, Terry.

How are you doing? G : Not too well.

I'm really having trouble figuring out this arithmetic assignment. I can add and subtract pretty well, but without a calculator it's difficult for me to multiply and divide. Hey, Olaf, I heard that you're excellent in math. B : My technique is that I try to imagine pictures in my mind, so the numbers aren't just figures on a page, but something I can apply to real life.

One way I do this is to imagine the numbers as if they were money. For example, if the equation is 753 minus 236, I think about seven dollars and 53 cents minus two dollars and 36 cents. It's five dollars and 17 cents, or 517. Easy! G : Wow, that does seem easier, for adding and subtracting.

But how do you apply this technique to multiplying and dividing? B : OK, suppose the equation is 200 times 30.

30 is three groups of 10. So, first I imagine 10 groups of people standing in a large field. Next to each group is a sign with the number 200 on it. At the front of the field is a huge sign with the number 2,000 on it, because 200 times 10 equals 2,000, right? But the problem requires 200 times 10 three times, so, I just add two more fields of people to my picture, with two more signs that say 2,000. Now I have 2,000 times three. The answer is 6,000!