Adding & Subtracting Integers

WARDEN AVE P.S.

Adding & Subtracting Integers

Number Sense & Numeration Unit #1

Grade 7 Math 2014-2015 School Year

This mini-unit will run from September 15-26 and must be handed in on Friday Sept. 26th by 3:45 pm

PART A: INTEGERS

What is an Integer? An integer is a number that has no fractional part, and no digits after the decimal point. We sometimes call them WHOLE NUMBERS. An integer can be positive, negative or zero. (Compare this to real numbers than can have digits after the point and can have fractional parts)

Example integers: +12 , +34 , -4 , 0

The following are real numbers and are not integers:

1.23 (cannot have decimal places) 12? (cannot have a fractional part)

Helpful ways to remember how Integers work:

The Number Line

Negative Numbers (-) (The line continues left and right forever.)

Positive Numbers (+)

Numbers on the left are smaller than numbers on the right.

Examples: 5 is smaller than 8 -1 is smaller than +1 -8 is smaller than -5

Now its your turn to place numbers along a number line. Remember to use the guide above to help you if you are stuck or confused.

SKILL BUILDER Please place the following numbers on the number line in their correct place.

-6 +12 -3 -12 +8 +7 0

END OF LESSON

Adding and Subtracting Integers

Numbers Can be Positive or Negative:

Negative Numbers (-)

Positive Numbers (+)

"-" is the negative sign.

"+" is the positive sign

No Sign Means Positive If a number has no sign it usually means that it is a positive number. Example: 5 is really +5 Adding Positive Numbers Adding positive numbers is just simple addition. Example: 2 + 3 = 5 is really saying "Positive 2 plus Positive 3 equals Positive 5" OR You could write it as (+2) + (+3) = (+5)

Subtracting Positive Numbers Subtracting positive numbers is just simple subtraction. Example: 6 - 3 = 3 is really saying "Positive 6 minus Positive 3 equals Positive 3" OR You could write it as (+6) - (+3) = (+3) Now for something a little different...

Subtracting a Negative is the same as Adding

Example: What is 6 - (-3) ? 6-(-3) = 6 + 3 = 9

Example: What is 14 - (-4) ? 14-(-4) = 14 + 4 = 18

RULE OF THUMB If the operational sign (what it's asking you to do) matches the number's integer sign, then you are ADDING.

And Positive and Negative Together ...

Subtracting a Positive or

Adding a Negative is

Subtraction Example: What is 6 - (+3) ?

6-(+3) = 6 - 3 = 3 Example: What is 5 + (-7) ?

5+(-7) = 5 - 7 = -2

RULE OF THUMB

If the operational sign (what it's asking you to do) does not match the number's integer sign, then you are SUBTRACTING.

QUICK REFERENCE

OPERATION

+ + + - - + - -

RESULT

+ +

Now you get to try out your new skills with some practice sheets. Ready to do it? Go!!!

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