Basic Math & Pre-Algebra For Dummies
Book image
Explore Book Buy On Amazon
When people first find out about subtraction, they often hear that you can't take away more than you have. For example, if you have four pencils, you can take away one, two, three, or even all four of them, but you can't take away more than that.

It isn't long, though, before you find out what any credit card holder knows only too well: You can, indeed, take away more than you have — the result is a negative number.

For example, if you have $4 and you owe your friend $7, you're $3 in debt. That is, 4 – 7 = –3. The minus sign in front of the 3 means that the number of dollars you have is three less than 0.

Here's how you place negative whole numbers on the number line.

image0.jpg

Adding and subtracting on the number line works pretty much the same with negative numbers as with positive numbers. For example, here's how to subtract 4 – 7 on the number line.

image1.jpg

Placing 0 and the negative counting numbers on the number line expands the set of counting numbers to the set of integers.

About This Article

This article is from the book:

About the book author:

Mark Zegarelli is a professional writer with degrees in both English and Math from Rutgers University. He has earned his living for many years writing vast quantities of logic puzzles, a hefty chunk of software documentation, and the occasional book or film review. Along the way, he’s also paid a few bills doing housecleaning, decorative painting, and (for ten hours) retail sales. He likes writing best, though.

This article can be found in the category: