7th Grade Math

Add and Subtract Integers

PART A B CD

Multi-Part

Lesson 2

Get ConnectED

GLE 0706.2.1

Extend understandings of

addition, subtraction,

multiplication and division

to integers. SPI 0706.2.5

Solve contextual problems

that involve operations with

integers. Also addresses

GLE 0706.1.8, GLE 0706.2.2,

SPI 0706.2.1.

88 Integers

Main Idea

Add integers.

Vocabulary

opposites

additive inverse

Add Integers

SCIENCE Atoms are made of

negative charges (electrons) and

positive charges (protons). The

helium atom shown has a total

of 2 electrons and 2 protons.

1. Represent the electrons in an
   atom of helium with an integer.


2. Represent the protons in an
   atom of helium with an integer.


3. Each proton-electron pair has a
   value of 0. What is the total charge
   of an atom of helium?

Combining protons and electrons in an atom is similar to adding

integers.

Add Integers with the Same Sign

Find - 3 + (-2).

• 6 - 5 - 40 - 3 - 2 - 1
  
  
  • 2 - 3 Start at 0. Move 3 units left to
    show -3.
    From there, move 2 units left to
    show -2.
  
  
  
  

So, - 3 + (-2) = -5.

a. - 5 + (-7) b. - 10 + (-4)

--

+

+

Add Integers with the Same Sign

Words To add integers with the same sign, add their absolute

values. The sum is:

• positive if both integers are positive.


• negative if both integers are negative.

Examples 7 + 4 = 11 - 7 + (-4) = - 11

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086_098_C2L2_895130.indd 88 12/29/09 4:00 PM