Converting Square Inches to Square Feet

Date: 02/26/98 at 17:14:51
From: Zack Meier, Megan Wolf
Subject: Area

How many square inches are in ten square feet?

Don't you take 12 times 10 to get an answer of 120 sq. in.?

Date: 02/26/98 at 17:30:28
From: Doctor Ethan
Subject: Re: Area

Hello Zack,

Great question.

I see how you are getting your idea, but I am afraid that it is a bit 
more complex than that.

The complexity comes because the question wants the answer in a 
different set of units than the units of the given information.

Because of that I am going to ask another question first to help us 
get on our way:

How many square inches are in one square foot?

To help us answer this, I am going to draw a square foot with the 
inches marked off.

       1 ft. = 12 inches
 - - - - - - - - - - - -
|                       |
|                       |
|                       |
|                       |
|                       |
|                       |  1 ft. = 12 in.
|                       |
|                       |
|                       |
|                       |
|                       |
|                       |
 - - - - - - - - - - - -

Now, given this drawing to find the number of square inches in a 
single square foot, we multiply 12 * 12  = 144.

According to your problem, we have 10 of these square feet, so we 
have

144 * 10 = 1440 sq. inches.

Hope that helps.

-Doctor Ethan, The Math Forum
 http://mathforum.org/dr.math/