| Operation |
Explanation |
Example |
| Multiply fractions |
Multiply both and
.
You don't need the same
denominators. |
1 3 1 X 3 3
--- X --- = ------ = ---
2 5 2 X 5 10
|
Fraction addition -
Same denominators |
Just add the numerators.
Keep the same denominator. |
1 2 1 + 2 3
--- + --- = ----- = ---
8 8 8 8
Don't add denominators!
|
| Changing denominators |
Divide the denominator you want
by the denominator you have,
then multiply by the numerator
to get your new numerator. |
3 ? 8/4 = 2; 6
--- = --- = ---
4 8 2 x 3 = 6 8
|
| Fraction addition with different
denominators |
If one denominator divides evenly into the
other, change to the higher denominator
and add. |
1 1 2 1 3
--- + --- = --- + --- = ---
2 4 4 4 4
|
| If the denominators don't divide evenly, then
multiply them
together to get your new denominator. Change denominators, then add |
Note: Since 3 doesn't go
into 5, use 3 x 5 = 15.
1 3 5 9 14
--- + --- = --- + --- = ---
3 5 15 15 15
|
Changing mixed numbers
to improper
fractions |
Find the number of unit fractions in the whole number, then add the fractional part of the mixed number. |
2 6 2 8
2 + --- = --- + --- = ---
3 3 3 3
Note: 2 is 6 thirds.
|
Changing improper fractions
to mixed
numbers |
Divide the numerator by the denominator to get the whole number. Then the fraction is the remainder over the denominator. |
8 8/3 = 2 with a
For --- remainder of 2 so
3 the mixed number
is 2 2/3
|
| Dividing fractions |
To divide one fraction by another, invert (turn upside-down) the second
fraction, then multiply. |
3/4 3 8 24
--- = --- X --- = --- = 6
1/8 4 1 4
Note: This means there are
6 eighths in 3/4.
|