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### Multiplying and Dividing Decimals

```
Date: 6/27/96 at 15:0:51
From: Sue Paul
Subject: Decimal Division, Multiplication

Dear Dr. Math,

I am going into Grade 6 next September.  On my report card my teacher
commented that I have difficulty with multiplication and division of
decimals.  Would you please explain these concepts?

Thank you,
Chris Paul
```

```
Date: 7/28/96 at 13:25:1
From: Doctor Robert
Subject: Re: Decimal Division, Multiplication

Hi Chris,

When multiplying decimals you follow this simple rule.  Multiply the
numbers totally disregarding the decimal points - that is, treat the
numbers as if they were whole numbers.  Then, after you have done the
multiplication, count the number of digits to the right of the decimal
in each of the numbers. ADD these numbers together and then count off
(from the right) this number of places in the answers and put the
decimal point there.

An example will help:

27.8 x 2.345

First multiply 278 x 2345 which is 651910.  Now, in the first number
there is ONE place to the right of the decimal and in the second
number there are THREE digits to the right of the decimal.
ONE plus THREE = 4.  Therefore, count four places in from the right of

To divide, you do the following.  Move the decimal point in the
DIVISOR to the right until the number becomes a whole number.  Move
the decimal point the SAME NUMBER of places in the dividend.  Then
proceed to divide the way you would with whole numbers.  The decimal
point in the answer lies directly above the decimal point in the
dividend.

An example:  27.84 divided into 434.6.  Move the decimal TWO places in
both numbers.  The problem then becomes:  2784 divided into 43460.

I hope that this helps.

-Doctor Robert,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
```
Associated Topics:
Elementary Fractions

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