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Integers
The integers are made up of three groups
of numbers:
• the positive integers
• the negative integers
• zero
Adding Integers
Example 1:
Example 2:
Example 3:
Example 4:
(+4) + (+5)
= 9
(-3) + (-7)
= - 10
(-7) + (+2)
=-5
(-1) + (+9)
=8
*Adding two positive
integers results in a larger
positive integer.
*Adding two negative
integers results in a larger
negative integer.
*Adding two integers with
different signs results in
an integer with the same
sign of the larger number.
Subtracting Integers
Example 1:
Example 2:
Example 3:
(+4) – (+1)
= 4 + (– 1)
=3
(+9) – (-5)
=9+5
= 14
(-2) – (-3)
= (-2) + 3
=1
*To subtract an integer,
add its opposite.
Multiplying and Dividing Integers
If the integers have the same sign (both
positive or both negative), the result of the
multiplication or division will be a positive
integer.
Example 1:
(2)(14)
=28
Example 2:
(-20)
(-2)
=10
Multiplying and Dividing Integers
(continued)
If the integers have different signs (a
positive and a negative), the result of
the multiplication or division will be a
negative integer.
Example 1: (-9)(4)
= -36
Example 2: 45
(-15)
= -3
Problems with Integers
Example 1:
An elevator went up three floors and down
two floors. How much higher or lower was the
elevator than when it started?
Solution:
(+3) + (-2)
=1
Therefore, the elevator was one
floor higher than when it started.
Problems with Integers
(continued)
Example 2:
Today’s high temperature was six degrees.
Today’s low temperature was four degrees
below zero. What was the change in
temperature?
Solution:
(+6) - (-4)
=6+4
= 10
Therefore, there was a ten-degree
change in temperature.
Practice
1.
3.
5.
5 – (-2) + 6
(-3) – (-4) – (-1)
(18)(-2)
2.
4.
6.
23 + (-6)
(-3)(-5)
(-40)
10
7. A plane is flying at 30 000 m. The
temperature outside the plane is -27oC. As
the plane lands, the temperature increases by
1oC for every 1000 m drop in altitude. What
is the temperature on the ground?
Homework

Worksheet