Reciprocals
A reciprocal is the value used to multiply a number by
to make the product 1
Find the reciprocal of 2:
2x
1
2
=1
What do we multiply 2 by to get
a product of 1?
Why? Think of multiplying fractions 2 x 1 = 2 = 1
2
2
1
Find the reciprocal of :
2
1
Multiplication is commutable
x2=1
2
Find the reciprocal of 3:
3x
1
3
=1
Find the reciprocal of 10:
10 x
1
10
=1
What do we multiply 3 by to get
a product of 1?
What do we multiply 10 by to get
a product of 1?
Reciprocals
Find the reciprocal of
3
4
x
4
3
3
4
:
=1
What do we multiply
a product of 1?
Remember how to multiply fractions: 3 x
4
4
3
Find the reciprocal of 0.7 :
7 x 10 = 1
0.7 = 7
10
Now change
10
10
into
7
7
a mixed number
So the reciprocal of 0.7 is 13
7
137
=
12
12
3
4
by to get
=1
Reciprocals
Find the reciprocal of 2 2
3
First write the mixed number as a top heavy fraction
8
3
then follow the same process
3
8
Now you know the principles the shortcut to finding a reciprocal
is to swap the numerator and denominator over
8 x
3
=1
Reciprocals
Now do these
Find the reciprocals of:
1.
6
2.
7
1
7
8.
0.3
3 13
3.
0.25
4
9.
0.125
8
4.
1
8
8
10.
1
3
4
4
7
5.
1
12
12
11.
1.25
4
5
6.
2
7
1
2
3
7.
3
11
3 23
1
6
12.
.
1.6
3
5