 # 1-7 Adding and Subtracting Integers Miss Tilton. 1-7 Adding Integers zero  Adding zero does not change an integer :  Zero property  Examples:  – 12.

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1-7 Adding and Subtracting Integers Miss Tilton

1-7 Adding Integers zero  Adding zero does not change an integer :  Zero property  Examples:  – 12 + 0 = – 12  0 + (– 88) = – 88

1-7 Adding Integers same sign  Adding integers with the same sign :  Find the sum  Keep the sign  Find the sum of – 5 + – 2

1-7 Adding Integers same sign  Examples of addition with the same sign : 1. 3 + 5 = 8 2. – 3 + (– 5) = – 8 3. – 50 + – 102 + – 5 = – 157  Try these… – 1 + (– 23) = – 5 + (– 2) + (– 7) = – 24 – 14

1-7 Adding Integers different signs  Adding integers with different signs :  Find the difference (of the absolute values)  Use the sign of the number with the larger absolute value  Find the sum of – 4 + 5

1-7 Adding Integers  Find the sum of 5 + (- 4)

1-7 Adding Integers different signs  Examples of addition with different signs : 1. 9 + – 6 = 3 2. – 34 + 5 = – 29 3. – 49 + 54 + – 14 = – 14  Try these… 2 + (– 10) = 30 + – 5 21 + (– 39) = – 8 25 – 18

1-7 Adding Integers  If you have no money on Monday. Your mom lets you borrow \$ 8 on Tuesday, and you pay her back from the \$ 10 you earn on Wednesday, how much money do you have?

1-7 Subtracting Integers positive :  Subtracting a positive using a number line :  Find the first value on the number line  Move to the LEFT (2 nd number)  Find the difference: 3 – 7  Find 3 on the number line  Move – 7 (or 7 spaces to the LEFT)  3 – 7 = – 4

1-7 Subtracting Integers  Find the difference: – 3 – 1  Find – 3 on the number line  Move – 1 (or 1 spaces to the LEFT)  – 3 – 1 = – 4  Try these… 2 – 4 = – 3 – 5 12 – 19 – 6 – 8 – 7

1-7 Subtracting Integers negative :  Subtracting a negative using a number line :  KEEP THE FIRST INTEGER THE SAME!!! ( + or – )  Change – – to +, because taking away a negative is adding  Follow the rules for addition  Find the difference: 3 – (– 6)  Change 3 – (– 6) to 3 + 6  Add  3 + 6 = 9

1- 7 Subtracting Integers  Try these… 2 – (– 4) = 3 – (– 5)= 12 – (– 9)= 2 + 4 = 3 + 5 = 12 + 9 = 6 8 21

1-7 Subtracting Integers  Find the difference: – 4 – (– 5)  Change – 4 – (– 5) to – 4 + 5  Add – 4 + 5  – 4 + 5 = 1

1-7 Subtracting Integers  Try these… – 2 – (– 4) = – 3 – (– 3)= – 12 – (– 9)= – 2 + 4 = – 3 + 3 = – 12 + 9 = 2 0 – 3

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