Differential Equations For Dummies
Book image
Explore Book Buy On Amazon
Sometimes, you want to talk about when two quantities are different. These statements are called inequalities. Four types of inequalities are (doesn’t equal), < (less than), > (greater than), and (approximately equals).

Doesn’t equal ()

The simplest inequality is , which you use when two quantities are not equal. For example,

2 + 2 5

3 4 34

999,999 1,000,000

You can read as “doesn’t equal” or “is not equal to.” Therefore, read 2 + 2 5 as “two plus two doesn’t equal five.”

Less than (<) and greater than (>)

The symbol < means less than. For example, the following statements are true:

4 < 5

100 < 1,000

2 + 2 < 5

Similarly, the symbol > means greater than. For example,

5 > 4

100 > 99

2 + 2 > 3

The two symbols < and > are similar and easily confused. Here are two simple ways to remember which is which:

  • Notice that the < looks sort of like an L. This L should remind you that it means less than.

  • Remember that in any true statement, the large open mouth of the symbol is on the side of the greater amount, and the small point is on the side of the lesser amount.

Approximately equals ()

Rounding numbers makes large numbers easier to work with. The , which means approximately equals, allows you to estimate answers using rounded numbers.

For example,

49 50

1,024 1,000

999,999 1,000,000

You can also use when you estimate the answer to a problem:

1,000,487 + 2,001,932 + 5,000,032

1,000,000 + 2,000,000 + 5,000,000 = 8,000,000

About This Article

This article is from the book:

About the book author:

Steven Holzner was an award-winning author of more than 130 books, of which more than 2 million copies have been sold. His books have been translated into 23 languages. He served on the Physics faculty at Cornell University for more than a decade, teaching both Physics 101 and Physics 102. Holzner received his doctorate in physics from Cornell and performed his undergraduate work at Massachusetts Institute of Technology, where he also served as a faculty member.

This article can be found in the category: