Transcript General School Presentation

Adding & Subtracting Mixed
Numbers
Adding Mixed Numbers
It’s usually easier to do these problems if you write
them vertically (up and down).
1
5
7
5
+2
7
Adding Mixed Numbers
Add the fractions, then add the whole numbers.
1
5
7
5
+2
7
_____
6
7
7
Remember:
make a common
denominator if you
need to!
Improper Fraction
Oops!
3
3
7
5
+2
7
_____
8
5
7
What if we get an improper fraction?
Improper Fraction
8
1
1
5  5 1  6
7
7
7
If we get an improper fraction - we fix it!
Subtracting Mixed Numbers
It’s usually easier to do these problems if you write
them vertically (up and down).
6
5
7
5
-2
7
Subtracting Mixed Numbers
Subtract the fractions, then subtract the whole
numbers.
6
5
7
5
-2
7
_____
1
3
7
Remember:
make a common
denominator if you
need to!
Borrowing
But, I can’t take 5 away from 1.
1
5
7
5
-2
7
Borrowing
You’re going to have to change the top fraction by
borrowing.
1
1
8
8
5  4 1  4   4
7
7
7
7
Borrow 1 from the 5 and change the mixed number to
an improper fraction.
Borrowing
Now your top fraction is big enough!
8
4
7
5
-2
7
____
3
2
7
Sneaky Trick
See what happened when we borrowed.
1
8
5 4
7
7
We added the 7 on the bottom of the fraction to the 1 on top to
make the 8.
That’s one shortcut that always works!
Remember:
To add or subtract mixed
numbers, write them
vertically.
The fractions need a L.C.D.
Add or subtract the fractions and then the whole numbers.
If you get an improper fraction, change it to a mixed number and
combine the whole numbers.
If you need to borrow from the whole number, add the bottom of
the fraction to the top to make the new top.