Adding and Subtracting Integers Objectives By the end

Adding and Subtracting Integers

Objectives By the end of this unit, the seventh grade will successfully • Add negative and positive integers • Subtract negative and positive integers

Quick Review • A positive number is greater than zero • A negative number is less than zero • Opposite numbers are numbers that are the same distance from zero in the opposite direction (ex. 5 & -5) • Absolute value is the distance from zero - + -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

Adding Integers: Same Signs If the sign of the numbers are same, then • Add the absolute values of the numbers 5 + ( 10) • Keep the sign of the numbers 5 + 10 = 15 -15

Adding Integers ( Same Signs) More Examples Example 1: Example 2: 11+ 6 -14 + (- 4) 11 + 6 = 17 14 + 4 = 18 = 17 = -18 If you don’t see a negative or positive sign in front of a number, then it is positive. Both signs are negative so the answer will have the negative sign.

Adding Integers: Different Signs If the signs of the integers are different, then. . . • Subtract the absolute values of the integers • Keep the sign of the number with higher - 5 + 15 absolute value 15 - 5 = 10 10 15 has the higher absolute value, so the answer will also be positive

Adding Integers ( Different Signs) More Examples Example 1: Example 2: -18 + 6 20 + (-14) 18 - 6 = 12 20 - 14 = 6 = -12 = 6 The answer is negative, because 18 has the higher absolute value. The answer is positive, because 20 has the higher absolute value.

Practice: Adding Integers Write down the answers on a separate sheet of paper. Check your answers by clicking the check below. 1. ) -5 + (-12) 2. ) -17 + (-5) 3. ) 16 + (-6) 4. ) 18 + 5 5. ) -23 + 4

Practice: Adding Integers Answers 1. ) -5 + (-12) = - 17 Same signs so add and keep negative sign 3. ) 16 + (-6) = 10 Different signs so subtract and keep positive sign because 16 > 6 2. ) -17 + (-5) = - 22 Same signs so add and keep negative sign 4. ) 18 + 5 = 23 Same signs so add and keep positive sign 5. ) -23 + 4 = -19 Different signs so subtract and keep negative sign because 23 > 4 Continue

Subtracting Integers • Rewrite the subtraction problem into an addition problem • Add the opposite of the second number • Follow -the 12 rules - 8 of addition - 12 + (-8) 1. Rewrite as addition problem = - 20 2. The opposite of positive 8 is -8. 3. Follow addition rules- same sign you add and keep negative sign

Subtracting Integers More Examples Example 1: Example 2: -11 – (- 3) 28 – 36 1. Rewrite as -11 + addition problem = -8 2. The opposite of positive -3 is 3 3. Follow addition rulesdifferent sign you subtract and keep negative sign 3 28 + (- 36) = -8 1. Rewrite as addition problem 2. The opposite of positive 36 is -36 3. Follow addition rulesdifferent sign you subtract and keep negative sign

Practice: Subtracting Integers Write down the answers on a separate sheet of paper. Check your answers by clicking the check below. 1. ) -7 – (-5) 2. ) -8 – 3 3. ) 16 – 25 4. ) 18 – (-11) 5. ) -23 – 15

Practice: Subtracting Integers Answers 1. ) -7 – (-5) 2. ) -8 – 3 = -11 = -7 + 5 = -8 + (-3) = -2 = -11 3. ) 16 – 25 = -9 = 16 + (-25) = -9 4. ) 18 – (-11) = 29 = 18 + 11 = 29 5. ) -23 – 15 = -38 = -23 + (-15) = -38 Continue

Jingle Sing this jingle to the melody of “Row, Your Boat” to help you memorize the rules of adding and subtracting integers. Click the sound icon. Same sign, add and keep, Different sign, subtract. Take the sign of the higher number, Then it’ll be exact! Change the minus to a plus, Change the sign of next, And all you do is add them up as if it were a plus. © Microsoft Office 2003 Continue

Assessment Question 1 Click on the correct answer. 1. ) -15 + (-13) a) -2 b) 28 c) -28 d) 2

Correct! Congratulations! You got the correct answer! -15 + (-13) is -28 © Microsoft Office 2003 Continue to Question 2

Oops! I’m sorry that was incorrect. Remember, same signs you add and keep the sign. In this case the signs are negative, so the answer is negative. -15 + ( - 13) is - 28 Continue to Question 2

Assessment Question 2 Click on the correct answer. 2. ) -11 - (-5) a) -6 b) 6 c) -16 d) 16

Correct! Congratulations! You got the correct answer! -11 - (-5) is -6 © Microsoft Office 2003 Continue to Question 3

Oops! I’m sorry that was incorrect. Remember, change into an addition problem. Add the opposite. The signs are different so you subtract and keep the sign of the higher number. -11 - (-5) = -11 + 5 = -6 Continue to Question 3

Assessment Question 3 Click on the correct answer. 3. ) 24 - 36 a) 12 b) -12 c) -60 d) 60

Correct! Congratulations! You got the correct answer! 24 – 36 is -12 © Microsoft

Oops! I’m sorry that was incorrect. Remember, change into an addition problem. Add the opposite. The signs are different so you subtract and keep the sign of the higher number. 24 – 36 24 + (-36) = -12 Continue to Question 4

Assessment Question 4 Click on the correct answer. 3. ) 18 + (-17) a) -1 b) 1 c) 35 d) -35

Correct! Congratulations! You got the correct answer! 18 + (-17) is 1 © Microsoft

Oops! I’m sorry that was incorrect. Remember, different signs you subtract and keep the sign of the higher number. 18 + (-17) is 1 Continue to Question 5

Assessment Question 5 Click on the correct answer. 5. ) -16 - 9 a) 7 b) -7 c) 15 d) -15

Correct! Congratulations! You got the correct answer! -16 – 9 is -25 © Microsoft

Oops! I’m sorry that was incorrect. Remember, change into an addition problem. Add the opposite. The signs are the same so you add and keep the sign. -16 – 9 -16 + (-9) = -25 Continue

Extra Practice Complete the following problems on a separate sheet of paper. 1. ) -22 + 11 6. ) -6 + 1 2. ) 53 + (-53) 7. ) -6 + 18 3. ) 2 – 5 8. ) 16 – (-34) 4. ) -6 – (-4) 9. ) 49 + (-39) 5. ) -8 – 5 10. ) 9 – 42 Continue

Congratulations You have just completed the program! Remember to sing the song and continue to practice. If you have extra time, go on the following websites for more practice. http: //www. aaamath. com/g 65 -add-3 negative. html http: //www. aaamath. com/g 65 -sub-negative. html http: //www. aaamath. com/g 65 -compareintegers. html © Microsoft Office 2003