Ceci's Scribe Post

Adding and Subtracting integers  (with no brackets)

Examples:

      (combining)

       - 7 + 2 = - 5

owe 7 & have 2 = owe 5

－ － － － － － －　＝　negative 5

＋＋

              -7

      <————— 0

<————|———|————>

　　——>-5

          +2 

we owed 7 dollars, but we have 2 dollars, how much do we have now?

we owed more than we have so the answer has to be negative, 

7-2 = 5, because we owed more, so the answer is -5.

     (removing)

- Ｔo add or subtract something that's not there,

   you must add zero pairs.

    (only happens when you see two negative sign or two subtract sign right besides each other...)

 Ｅxample:

        

                (-7) - (-10) = +3 

owe 7 remove owe 10= have 3

－－－－－－－－－－－－－－－－－

　　　　　　　＋＋＋＋＋＋＋＋＋＋　＝　+３

we owed 7 dollars, but we want to re move 10 dollars from 7 dollars,

 you can't do it, so we have to add zero pairs, we have to add 10 

zero pairs, then remove 10 dollars, we have 7 zero pairs and 3 dollars

 left, we cross out the zero pairs then we get positive 3 (3 dollars).

more examples:

             (-1) - 2 = -3  we don't need to remove because the two negative signs aren't beside each other.

owe 1 & owe 2 = owe 3

             5 - (-2) = +7

have 5 remove owe two = have 7

            -7 + 8= +1

  owe 7 & have 8= have 1

           

            2 + (-5) = -3

  have 2 & owe 5 = owe 3