3-1 NotesAdd and Subtract Signed Numbers

objecive: 1. add and subtract using a number line or rules.2. use addition properties to find sums.

A number line can be used to show addition of two numbers.

Start at 0.

Move to the right to add a positive number.

Move to the left to add a negative.

http://www.eduplace.com/cgi-bin/schtemplate.cgi?template=/kids/mw/manip/mn_popup.thtml&filename=nmbl_int&title=Number%20Line&grade=4

EXAMPLE 1: Use a number line to add.

A. 2 + 6B. 5 + (-3)C. -4 + (-1)D. -7 + 2E. 8 + (-8)

Two numbers the same distance from 0 but in opposite directions are known as OPPOSITES.

Absolute Value

To add numbers with the same signs,

To add numbers with different signs,

Example 2: ADD

A. -9 + (-3) B. 4 + (-16) C. -5 + 13 D. -12 + 0

Property of Addition

of Signed Numbers

Example 3: Subtract

A. -12 - 3 B. 6 - (-9) C. -14 - (-6) D. 5 - 15

Example 4:

The highest temperature recorded in Little Rock, Arkansas is 112 degrees Fahrenheit. The lowest is -5 degrees Fahrenheit. Find the difference between the high and low temperatures for Little Rock.