Adding Mixed
Numbers
8.2
What would you do?
+
3
5
1/8
3/8
Procedure
+Add the whole-number
parts
+Add the fraction parts
+Rename into simplest
form
Practice Renaming
4 7/5
8 4/3
2 7/4
Practice
O MJ page 254
O Complete independently.
O Stand behind your chair
when you are finished.
Procedure for adding unlike
denominators
+ Add the whole-number parts
+ Find a common denominator
+ Add the fraction parts
+ Rename into simplest form
Spiral Practice
2 ½ + 4 3/8= 6 7/8
5 2/3 + 1 5/6= 7 1/2
3 4/5 + 2 ¼= 6 1/20
6 5/6 + 3 3/5= 10 13/30
1 7/8 + 8 1/6= 10 1/24
Pattern
O Look at the following problems and determine a pattern:
1 + 1 = 3
1
2
6
1 + 1 = 5
2
3
6
1 + 1 = 7
3
4
12
1 + 1 = 9
4
5
20
Solution
O When you are adding two unit fractions
(numerators are 1), the sum will always be
the sum of the denominators
product of the denominators
(How cool is that!?!)
Pattern
Take a look again to see the pattern:
the sum of the denominators
product of the denominators
1 + 1 = 3
1 2
6
1 + 1 = 5
2 3
6
1 + 1 = 7
3
4 12
1 + 1 = 9
4
5 20
Practice the Pattern
O Use the pattern on these fractions –
remember this only works with unit fractions
1/3 + 1/5 =
1/12 + 1/ 4 =
1/9 + 1/7 =
1/5 + 1/15 =
Subtracting Mixed Numbers
(notes)
O Subtract the fractions first in
case you need to borrow from the
whole number.
O Be sure you have common
denominators before subtracting
O Subtract the whole numbers.
Ta Da you are a genius!
Let’s Practice Borrowing
O 7 ¼ - 5 3/5= 1 13/20
O 6 1/2 - 3 2/3= 2 5/6
O 9 1/3 - 5 2/4= 3 5/6
O10 1/5 - 3 ½= 6 7/10
What about these?
O 6 - ¼ = 5 3/4
O 8 – 3 2/3= 4 1/3
O4 3/5- 1 4/5=
2 4/5
O5 1/6 – 2 5/6= 2 1/2
Mixed Number Spin
O Make a spinner from a
paper clip and a pencil
point
O Use the mixed numbers
from your spin to create
true number sentences
O The first person to create
10 true sentences is the
winner