Math 6High ( Period 3)

Adding Integers on a Number Line 4.2

We used the number line to model adding two positive numbers—and we developed a similar pattern for adding integers.  

Please look at our textbook page 171 to see the examples of adding integers—the book uses the color blue to indicate a positive number’s movement along the number line and the color red to indicate movement to the left representing a negative number.

You will discover that

 2 + (-5) = -3

-6 + 8 = 2

Two numbers are opposite if they are the SAME distance from 0 on the number line but are opposite sides of ZERO. 

For example -3 and 3 are opposites because they are both 3 units away from zero.

Again -3 can be read as “the opposite of 3” as well as “negative 3”. 

The expressions –(-3) can be read as “the opposite of negative three”  which would be +3

Inverse Property of Addition
Words: 

The sum of a number and its opposite is zero

Algebraic: 

a + (-a) = 0