 # Adding and Subtracting Integers “All things excellent are as difficult as they are rare” Spinoza.

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Adding and Subtracting Integers “All things excellent are as difficult as they are rare” Spinoza

Remember numbers can be positive or negative

NO SIGN MEANS POSITIVE “ – ” means the number is negative “ + ” means the number is positive No sign usually means the number is really a positive number. Example 5 is really +5

Adding and Subtracting positive numbers is just simple addition and subtraction Example: 2 + 3 = 5 is really saying "Positive 2 plus Positive 3 equals Positive 5" You could write it as (+2) + (+3) = (+5)

AND…. Example: 6 − 3 = 3 is really saying "Positive 6 minus Positive 3 equals Positive 3" You could write it as (+6) − (+3) = (+3)

Balloons and Weights This basket has balloons and weights tied to it: 1)The balloons pull up (POSITVE) 2) And the weights drag down (NEGATIVE)

Here is what adding and subtracting positive numbers looks like You can add balloons (you are adding positive value) THE BASKET GETS PULLED UPWARDS (POSITIVE)

Or you can take away balloons The basket gets pulled down

What if you subtract negative numbers? You take away weights (you are subtracting negative values) The basket gets pulled upwards (POSITIVE)

So…. Subtracting a Negative made the basket GO UP!?! So subtracting a Negative is the same as Adding!!!!

General Rule for SUBTRACTING integers

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

NOW…. Solve 1) 14 – (-4) 2) 20 – (-10) 3) 15 – (-29)

And Positive and Negative Together… Subtracting a positive or Adding a negative is SUBTRACTION

Example 1) What is 6 – (+3) ? 6 – (+3) = 6 – 3 = 3 2) What is 5 + (-7) ? 5 + (-7) = 5 – 7 = -2

Now solve… 1. 6 + -8 2. 10 + -5 3. 35 + -55

The Rules Two like signs become a positive sign Two unlike signs become a negative sign

Example + (+):3 + (+2) = 3 + 2 = 5 - ( - ): 6 – (-3) = 6 + 3 = 9 + ( - ): 7 + (-2) = 7 – 2 = 5 - ( + ): 8 – (+2) = 8 – 2 = 6

So, all you have to remember is Two LIKE signs become a POSITVE sign Two UNLIKE signs become a NEGATIVE sign