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### Solving Problems Without Paper

```
Date: 9/1/95 at 19:9:51
Subject: working problems in my head

My name is Megan Mead.  I'm in seventh grade and I'm having trouble
when we have to do problems in our head instead of on paper.  Do you have
some ideas on what will help me?
```

```
Date: 9/2/95 at 11:47:11
From: Doctor Ken
Subject: Re: working problems in my head

Hello!

To tell you the truth, I'm actually not all that good at doing numbers in my
head either.  I have gotten better at it though, and here's what has helped
me.

I don't try to do the addition and multiplication the way that people learn
in school, starting on the right and working toward the left. I actually
start on the left and go right.  I find it easier because you don't have to
remember the numbers in the reverse order you really want them in.  For
example, if we had 342 + 831, here would be my steps:

342
+831
----
11

342
+831
----
117

342
+831
----
1173

The only weird part is when you have to carry numbers.  Then you have to go
back and change what you had before:

746
+487
----
11

746
+487
----
122

746
+487
----
1233

I do the same thing for multiplication, but that gets a little more tricky
to remember all the steps.  Can you figure out how to do that?

-Doctor Ken,  The Geometry Forum
```
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