|
|
Here are some
examples: |
|
number |
its
multiplicative inverse |
|
2/3 |
3/2 or 1 ½ |
|
8/13 |
13/8 or 1⅝ |
| 4
4/5
or 24/5 |
5/24 |
| 4
½ or 9/2 |
2/9 |
| 6
or 6/1 |
1/6 |
Did you notice that:
-
before you find the
reciprocal of a mixed number, you must first change it to an improper
one?
-
and before you find
the reciprocal of a whole number, you must first write it as a fraction
with a denominator of 1.
Now, why is
it necessary to know this?
|
Dividing by a fraction is the same as
multiplying by its reciprocal.
e.g. 8
÷ 2/3 = 8 x 3/2
and 3
÷ 1/2 = 3 x 2/1
|
-
Remember:
All
numbers except 0 have a multiplicative inverse. The inverse of 5 is 1/5.
But 0 has no inverse because you can't multiply any number by it to get
1. Zero multiplied by any number is zero, therefore, 0 is the only
number that does not have a multiplicative inverse.
HOW can that be
true? WHY does that work? The next lesson, using fraction
pieces, shows you HOW with a picture!
|
