Download 1 - Bibb County Schools

Time to conquer our
fraction phobias!
A mixed number has a whole number
part and a fraction part. Such as
3 - Whole
number part
3
2
5
2/5 - Fraction part
We connect the whole-number name to
the fraction name with the word “and.”
This mixed number is read three AND
two fifths.
Follow these steps
1. Find a common denominator.
2. Add or subtract the whole number part.
3. Add or subtract the numerators.
4. Keep the common denominators.
5. Simplify.
Let’s try an
example.

1. Common denominator.

2. Add whole number.
3. Add numerators.
 4. Keep the common
denominators.
 5. Simplify.

1
4
3
3
+24
_____________________
5
4
4
Since 4
divided by
4 = 1…
Try a
harder
problem.
2
1
4
+3
3
8
Remember to check to
see if the smaller
denominator will divide
evenly into the larger
denominator.
4 will divide evenly into 8; therefore, 8 is the least common
denominator (LCD).
1
2 4
+3

3
8
X
x
2
2
2
=
8
= 3
8
4x2=8
1x2=2
The
renamed
fraction is
2 eighths.
1. Common denominator
Multiply the fraction part by another
name for 1. The special, select name for
1 is 2 divided by 2.
2
+3
5
1
4
X
3
8
x
2
2
2
=
8
= 3
8

2. Add whole number.

3. Add numerators.

4. Keep denominator.
5. Simplify.
5
8
Tim and Ken are runners. On
7
Wednesday Tim ran 4 8 miles and
2
Ken ran 3 3 miles. How much
further did Tim run?
Tim and Ken are runners. On
7
Wednesday Tim ran 4 8 miles and Ken ran
2
3 3 miles. How much further did Tim run?
4
7
8
- 3
2
3
_________________________
Remember, when the smaller
denominator will not divide
evenly into the larger
denominator, you must find the
least common multiple for the
denominator.
4
7
8
- 3
2
3
_________________________
Multiples of 8: 0, 8, 16, 24, 32, …
Multiples of 3: 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, …

1. Multiply the fraction part by a name
for one to get a common denominator.
7
7 x 3 = 21
3
21
=
x
3
8 x 3 = 24
24
8
4
-3
2
3
x
8
8
16
= 24
2 x 8 = 16
3 x 8 = 24
Don’t give up. We are
almost there. See you on
the next slide.
4
7
8
x
3
21
=
3
24
-3
2
3
x
8 = 16
8
24
1



2.
3.
4.
5.
5
24
Subtract whole number.
Subtract the numerators.
Keep the denominators.
Simplify (if necessary).
Yea!
Jeffrey is baking
brownies. So far he
1
has put in 2 4 cups of
2
flour and 1 cups of
3
sugar.
What is the total amount of ingredients
that he already has in his bowl?
2
1
4
+1
2
3
It gets easier if
you practice.
Multiples of 4: 0, 4, 8, 12, 16, …
Multiples of 3: 0, 3, 6, 9, 12, 15,
…
1. Multiply the fraction part by a name
for one to get a common denominator.
2
1
4
x
+1
2
3
x
3
3
3 = 12
4 = 8
4
12
1x3=3
4 x 3 = 12
2x4=8
3 x 4 = 12
“I think I can.
I think I can. I
think I can.”
2. Add whole number.
3. Add numerators.
2
+1
3
1
4
x
2
3
x
3
3
3 = 12
4 = 8
4
12
11
12
5. Simplify.
4. Keep denominator.
Now for
a tricky
problem.
1
3
1
3
4 -1
5
?
6
5
6
Is smaller than
If so,
borrowing may be necessary but
perhaps there is an easier way.
4
- 1
1
3
5
6
1
5
Is 3 smaller than
?
6
One way to compare
fractions is to visualize
them.
1
3
<
5
6
1
3
is smaller than
4
-1
5
6
1
3
5
6
Don’t worry. Make improper fractions
of the mixed numbers.
Make improper fractions.
4
=
-1
=
13
3
11
6
Now follow the steps and
shoo your phobias away.
3x4+1
6x1+5
1. Find common denominator.
4
-1
13
=
3
11
=
6
x
x
2
2
=
=
26
6
11
6
2. There is no whole number.
3. Subtract the numerators.
4
1
3
-1
5
6
13
=
3
11
=
6
x
2
2
x
4. Keep the denominators.
=
=
26
6
11
6
15
6
Simplify.
4
1
3
-1
5
6
15 ÷.
6
13
=
3
11
=
6
3
3
x
2
2
x
=
5 =
2
26
6
11
=
6
15
6
=
1
2
2
Now it’s time
to show what
you know.