What are adding and subtracting integers?

Adding and subtracting integers is when you add or subtract two or more positive or negative numbers together. 

You can add and subtract integers using visual models or a number line.

Rules:

• if the two integers have the same sign, then add the two integers and keep the sign the same as the two integers.

• If the two integers have different signs, subtract the two numbers, and keep the sign of the larger number.

Evaluate the following:

a. 14 – (-6) c. 14 – (+6)

b. -14 – (6) d. -14 – (-6)

Solution:

a. 14 – (-6) = 14 + (+6) = 14 + 6 = 20

b. -14 – (6) = -14 + (-6) = -20

c. 14 – (+6) = 14 + (-6) = 8

d. -14 – (-6) = -14 + (+6) = -8

Evaluate:

• 7 + (-4) - (-9) + 4 - 5

To perform these operations, we will first rewrite all of the subtraction, as adding the opposite.

7 + (-4) - (-9) + 4 - 5 = 7 + (-4) + 9 + 4 + (-5) =

Evaluate:

• 20 + (-10) - (-5)

• 8 - 9 + (-40) - (-12) + 4

Changing all of the subtraction to adding the opposite, and then adding from left to right, we have:

• 20 + (-10) - (-5) = 20 + (-10) + 5 = 15

• 8 - 9 + (-40) - (-12) + 4 = 8 + (-9) + (-40) + 12 + 4 = -25

Evaluate: 18 + (-7) – 5 – (-4)