Subtracting Decimals

Date: 09/16/97 at 08:59:29
From: Emileigh Merce
Subject: Subtraction

I can't figure out what 1100000 - 1100000 - 700000 - 123456789 - 14 = 
because I don't know how to do decimals. I've tried a calculator, but 
it's too long. Please help me!

Date: 11/10/97 at 12:17:45
From: Doctor Sonya
Subject: Re: Subtraction

Dear Emileigh,

Your question is hard for me to answer because you ask about decimals, 
but there aren't any decimals in the numbers you wrote down. I'll tell 
you how I subtract decimals, and maybe that will help some.

The first thing to remember is that subtracting decimals is almost the 
same as subtracting whole numbers (numbers without decimals). If you 
are going to subtract one number from another, you set it up like 
this, right?:

427350
- 3447
------
423903

If you're going to subtract a decimal from another decimal, you set it 
up the same way, but you put the decimal points right above each 
other, like this:

10.67
-4.33
-----
  ?

Then you put the decimal point in the same place in the answer, and 
continue to subtract as if it's not there.  Here's my example:

First I put the decimal point in:

10.67
-4.33
-----
  .

Now I do the subtraction:
10.67
-4.33
-----
 6.34

If the two decimal parts of the numbers are not the same length, just 
fill in the shorter one with zeros.

 45.89
-23.5774
--------
   ?

becomes
 45.8900
-23.5774
--------
   ?

and then you do the subtraction the way we did above.
 45.8900
-23.5774
--------
 22.3036

Here's one more example for you to do yourself:

 20.567
-17.43386
---------
   ?

I hope this helps.  Write us back if you ever have any more questions.

-Doctor Sonya,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/