Slide 2 The upside of negativity Subtracting Negative Integers!
Video # 8 about integers Slide 3 Negative numbers. Negative numbers
are the opposite of positive numbers. +++ - - - +++ - - - Slide 4
Slide 5 6 + -2 Is the same as 6 2 Which is 4. If this is confusing,
review the earlier lesson on adding integers. Slide 6 -- change two
things to keep balance Change subtraction to adding Change the sign
of the next number Heres your starting point is it positive or
negative? Slide 7 8 2 = 8 + - 2 = 6 same sign, add and keep
different sign, subtract! Keep the sign of the bigger number then
youll be exact Slide 8 15 5 = 5 15 = 9 8 = 8 9 = 20 5 = 5 20 =
Slide 9 15 5 = 5 15 = 9 8 = 8 9 = 20 5 = 15 5 20 = -15 Slide 10 -4
5 = -4 + -5 = -9 -4 -9 What it means is more important than what it
looks like If you have already lost 4 (pounds, pickles, whatever!)
and you lose five more, youve lost 9. Slide 11 Review with these
problems be sure youre doing the right operation. Watch for trick
questions! -2 2 is 4. 8 5-50 2510 - 9 -1 + 6-30 + 209 - 10 1 - 6100
5 -100 - 1 5 10 -9 + 101 - 100 Slide 12 Review with these problems
be sure youre doing the right operation. 8 5-50 2510 - 9 -1 + 6-30
+ 209 - 10 1 + -6100 5 -100 - 1 5 10 -9 + 101 - 100 Slide 13 Review
with these problems be sure youre doing the right operation. 8 5
=3-50 + -25=-75 10 + -9= 1 -1 + 6 =5-30 + 20= -10 9 + 10= -1 1 + 6=
-5100 + -5 =95-100 + -1 =-101 5 10= -5 -9 + 10 = 11 100 = -99 Slide
14 Slide 15 8 1 = 7, right?... But thats subtracting a positive
number. Slide 16 8 1 = 7 we take it away. what is 8 (-1)? Whats the
opposite of taking away? Adding. Im going to change that to adding
the opposite and go the *opposite direction. 8 + (regular, good old
fashioned POSITIVE) 1. Slide 17 The soap opera version? Subtraction
is taking away, right? A negative thing is bad, right? If I take
away a bad thing like that nasty smelling thing in my refrigerator
thats like *giving* me a *good* thing ADDING. Slide 18 The
difference between 8 and 3 is 5, and 8-3 is 5. The difference
between 8 and negative one is 9. 8 is nine more than negative one.
8 Slide 19 I get to add Slide 20 (Honestly the rules dont change )
Slide 21 You have to change two things the subtraction to addition,
and the number from negative to positive. 6 2 = -6 2 = 6 - -2 = -6
- -2 = Slide 22 You have to change two things the subtraction to
addition, and the number from negative to positive. 6 2 = 4-6 2 =
-8 6 - -2 = 8-6 - -2 = -4 Slide 23 Remember ALWAYS ALWAYS ALWAYS
Change two things. Adding is *not* the same as subtracting; Forward
is not the same as backwards. But if you turn around **again**
youre back where you started. Slide 24 10 (-1)-10 - -1 3 - -3-3 -
(-3) 4 (-4)-4 - -4 5 - (-5)-4 - (-5) This will matter more when
youre learning multiplication: Parentheses are used to wrap a
number or expression to show things that belong together. It can be
confusing; if two numbers are written like this (3) (4), that means
to multiply them. Its not because of the parentheses, though; its
because math people decided that if they didnt write anything, it
meant to multiply. Slide 25 10 (-1)= 11-10 - -1 = -9 3 - -3=6-3 -
(-3)= 0 4 (-4)= 8-4 - -4 = 0 5 - (-5)= 10-5 - (-5) = 0 Slide 26
Heres another example where what it means is more important than
what it looks like. 8 8 is zero 139 139 is zero anytime you take
away exactly the same thing you started with, youre back at zero
even if its a negative number. So, negative 133 minus negative 133
is 0. -3 - (-3)= 0 -34343 - (-34343) = 0 -4 - -4 = 0 -5 - (-5) = 0
Slide 27 Two main rules if youre adding, Same sign, add and keep
different sign subtract keep the sign of the bigger number then
youll be exact. If youre subtracting, change two things so you are
adding the opposite. (remember the trick questions : -2 -2 = -4 -2
(-2) = 0 Slide 28 -5 + 5 = -5 5 = 5 + 5 = 5 5 = 5 (-5) = -5 (-5) =
100 1 = - 100 99 = 100 (-99) = 75 74 = - 74 (-1) = - 13 + 13 =
Slide 29 -5 + 5 = 0 -5 5 = -10 5 + 5 = 10 5 5 = 0 5 (-5) =10 -5
(-5) = 0 100 1 = 99 - 100 99 = -199 100 (-99) = 199 75 74 = 1 - 74
(-1) =- 73 - 13 + 13 = 0 Slide 30 -5 + 5 = -5 5 = 5 + 5 = 5 5 = 5
(-5) = -5 (-5) = You make up six problems using that as a model,
and explain why the first and last ones add up to zero. Slide 31
http://www.helpingwithmath.com/printables
/worksheets/numbers/int0601integers_02.ht m is a nice practice
sheet you can click for the answers.
http://www.helpingwithmath.com/printables
/worksheets/numbers/int0601integers_02.ht m aaamath.com has
practice under addition and subtraction scroll down to find
integers. aaamath.com
