^

How to change subtraction of integers into an addition — and WHY it works

In this pre-algebra or grade 7 math lesson, I show how integer subtraction works, first of all, based on two simple patterns. If we continue them logically, we see that subtracting an integer works the same as adding the opposite of that integer. The second pattern makes it especially easy to see WHY subtracting a negative integer changes into addition. It's the shortcut of a double negative turning into a positive.

Then I solve several simple examples, such as −6 − (−2) and others. Next, I show how subtraction of integers works on a NUMBER LINE (as jumps).

In the latter part, we study more complex examples of mixed integer additions and subtractions. With those, you can either solve the operations one by one (from left to right) — or convert each subtraction into an addition first, then add all the positives separately and all the negatives separately, and lastly add the two sums.

Tengo una versión español de este video también.

Addition of integers — a video lesson

Multiplication of integers — a video lesson

Math Mammoth Integers — a self-teaching worktext with explanations & exercises for all operations with integers

Math Mammoth Grade 7 complete curriculum

Back to the integer videos index

Back to all videos index

WAIT!

Receive my monthly collection of math tips & resources directly in your inbox — and get a FREE Math Mammoth book!

You can unsubscribe at any time.

Math Mammoth Tour

Confused about the different options? Take a virtual email tour around Math Mammoth! You'll receive:

An initial email to download your GIFT of over 400 free worksheets and sample pages from my books. Six other "TOURSTOP" emails that explain the important things and commonly asked questions concerning Math Mammoth curriculum. (Find out the differences between all these different-colored series!)

This way, you'll have time to digest the information over one or two weeks, plus an opportunity to ask me personally about the curriculum.
A monthly collection of math teaching tips & Math Mammoth updates (unsubscribe any time)

"Mini" Math Teaching Course

This is a little "virtual" 2-week course, where you will receive emails on important topics on teaching math, including:

- How to help a student who is behind
- Troubles with word problems
- Teaching multiplication tables
- Why fractions are so difficult
- The value of mistakes
- Should you use timed tests
- And more!

A GIFT of over 400 free worksheets and sample pages from my books right in the very beginning. A monthly collection of math teaching tips & Math Mammoth updates (unsubscribe any time)