Math 7 - 2.5

2.5 Subtracting Integers on a Number Line.
Focus: Subtract Integers on a Number Line.

Note: subtraction is finding the difference between two numbers

* Using tiles, subtract (-7) - (-2)...

* To subtract numbers on a number line, add the opposite

Eg. (+9) - (-19) is the same as (+9) + (+19)...both equal +28

Follow the same steps you used to complete addition equations on number lines:
1.) Draw an arrow from 0 to the first integer.
2.) Draw an arrow from the first integer, counting the number of spaces that the 2nd integer indicates.
3.) Where your arrow stops is the answer to your equation.

Except this time.....ADD THE OPPOSITE INTEGER! ****Turn your subtraction equation into an addition equation and change the 2nd integer from negative to positive (or positive to negative) before you do anything else!***

Examples - Let's work through these together! Use tiles to solve the subtraction equations, then model the equation on the number line:

Practice!
Homework for tomorrow:
- pgs. 73-75 #s 1 - 11 (odd)