Page 45 - Math Smart - 7

The negative of a
Work out-1 -{-3).
negative number is a
Let us use the number discs to help us.
positive number. -(-3)
To find the negative of -3, flip the number disc as shown: makes (+3).
00© flip

So, -1 - (-3) is the same as -1 + 3:
-1)
© i7
same
We get 2.
Explain
On the number line, you would start at -1 and move to the right by 3 units. number
number

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

So, -1 -(-3) = 2.

Check My
Understanding

Let's practise adding and subtracting integers.
Work out the values,
a) 3 + b) 3 + (-1)
1
c) -3+1 d) -3 + H)
e) 3-(-1) f) -3-(-1)
g) -11-18 h) 15-(-15)
i) ^0+11 j) -18-14

Work out the values,
a) 7-8 + 6 b) 10-(-6)-2
c) -3-9-5 d) 4 + (-5) +
1
e) 6 + (-9)-(-1) f) -3 + (-2) + (-1)
g) -8 + 9- 9 + 8 h) -4-2-7
Think about some
Maggie parked her car on one of the many shopping mail levels. examples of how
She forgot which level she had parked her car on. However, she integers are used in the
remembered that she had taken the elevator up five floors, to the 4^^ world we live in.
floor. On which floor level did she park her car? Discuss how integers
o Work out the following. help us to determine
a car speeding over
a) -4-(-1) b) 8-(-5)
the limit, indicating an
0 -7-(+2) d) (-14)-(-4)
overpaid bill, or going
e) -7-(-7) f) (10)-(+9) to the underground
g) (4)-(-12) h) (20) - (-30) carparks in a mall.
j) _7_(_8)-(+1)
j) -8-(+1)-(-2)
k) -2-(-1)-(+8) I) 4_(_3)_(_9)

o