Adding Integers

2. Adding Integers

3. Adding Integers Assume there is a battle going on. The battle is between the good guys and the bad guys. If two good guys meet on the battle field, will they join forces, or will they fight? Of course, they will join forces to help each other out. If two bad guys meet on the battle field, will they join forces, or will they fight? Of course, they will join forces to help each other out. If a good guy runs into a bad guy, what will happen? They will “cancel” each other out.

4. Adding Integers • This is an analogy for adding integers where the yellow army men (the good guys) represent positive integers, and the red army men (the bad guys) represent negative integers. • If you have twopositive integers, and you add three positive integers, they will join forces to give five positives • So: 2 + 3 = 5

5. Adding Integers • Similarly, if you have four negatives, and you add six negatives, they will join forces to give ten negatives. • So: -4 + -6 = -10 • However, if you have five negatives, and you add three positives, they will fight:

6. Adding Integers • Any time you have one positive and one negative, it is called a zero pair • Why do you suppose that is? • Because their sum equals ZERO. • Therefore, you can remove them. • There are two reds (-2) left. -5+3=-2

7. Adding Integers • Add the following: 9 + -2 -6 + 5 -3 + 6 7 3 -1

8. 6 + -13 -7 -15 + -2 -17 22 + 3 25 -16 + 5 -11 -19 + -5 -24 64 + -64 0 Adding Integers

9. Adding Integers • If the signs are the same…. • If the signs are different… Add the numbers Keep the same sign Subtract the numbers Take the sign of whatever you had more of (+ or –)

10. The Integer Song Here is a rule that you must know when you are adding integers If signs are the same If signs are the same If signs are the same Then simply add the numbers

11. Verse 2 Another rule that you must know when you are adding integers If signs are different If signs are different If signs are different Then just subtract the numbers