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### Integers in Daily Life

Date: 05/31/2002 at 10:29:41
From: Jessica, Tracy, and Mike
Subject: integers

Hi,

We want to ask you how integers are used in daily life?
Thank you.

Sincerely,
Jessica, Tracy, and Mike

Date: 05/31/2002 at 12:31:33
From: Doctor Peterson
Subject: Re: integers

Hi, Jessica, Tracy, and Mike!

You just used an integer when you typed your age in! Anytime you
count anything, you are using integers. That's because integers
are all the positive and negative whole numbers, _including_ the
natural numbers you first learned. So you've been using integers

Perhaps you really meant, how are negative numbers used (since
you were probably introduced to the term "integer" as a way of
extending the natural numbers to include negative numbers)?

If you live in a cold climate, you use negative numbers (often
negative integers) to tell the temperature in the winter. That is
more likely if you live in a country where the Celsius scale is
used.

If you do any kind of science or engineering, you will find
negative numbers essential. Even when quantities we measure, like
mass or pressure, are always positive, we need negative numbers
to describe changes or differences or rates of change, because
quantities can both increase and decrease.

Until negative numbers were invented, algebra was extremely
difficult, so many inventions were held back. Much of the
technology you take for granted ultimately depends on negative
numbers!

Money also can increase and decrease, so you need negative
numbers in finance--though in that world they are only slowly
catching up with the modern world and learning to write "-10"
instead of "(10)" or use "red ink" to indicate negative numbers!

You might find these answers interesting:

http://mathforum.org/library/drmath/view/57152.html
http://mathforum.org/library/drmath/view/59049.html
http://mathforum.org/library/drmath/view/52475.html

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