Monday, March 12, 2007
If the fractions aren't in a mixed number.. heres the way to do it.
2/3 - 3/5 = 10/15 = 9/15 = 1/15 .. multiply the denominators by each other ( 5 x 3 =15) .. then cross multiply 2 x 5 = 10 and 3 x 3 = 9 .. fraction is now 10/15 and 9/15 then subtract 10 from 9 and that gives you 1/15 ..
If the fractions have different denominators
1) Find the least common denominator.
2) Find the equivalent fraction using this denominator.
3) Subtract the fractions, if you could reduce then you should.
There are 3 Simple Steps to add fractions:
Step 1: Make sure the bottom numbers (the denominators) are the same
Step 2: Add the top numbers (the numerators). Put the answer over the the same denominator as in step 1
Step 3: Simplify the fraction.
Step 1. The bottom numbers are already the same. Go straight to step 2.
Step 2. Add the top numbers and put the answer over the same denominator:
|1||+||1||=||1 + 1||=||2|
Step 3. Simplify the fraction:
(If you are unsure of the last step see the equivalent fractions page)
Step 1. The bottom numbers are now different. We need to make them the same:
Step 2. Add the top numbers and put them over the same denominator:
|2||+||1||=||2 + 1||=||3|
Step 3. Simplify the fraction:
Adding Fractions with Different Denominators
To Add Fractions with different denominators:
- Find the Lowest Common Denominator (LCD) of the fractions
- Add in the new numbers to the fractions to have the LCD
- Add the numerators of the fractions
- Simplify the Fraction
Example: Find the Sum of 2/9 and 3/12
- Determine the Greatest Common Factor of 9 and 12 which is 3
- Either multiply the denominators and divide by the GCF (9*12=108, 108/3=36)
- OR - Divide one of the denominators by the GCF and multiply the answer by the other denominator (9/3=3, 3*12=36)
- Rename the fractions to use the Least Common Denominator(2/9=8/36, 3/12=9/36)
- The result is 8/36 + 9/36
- Add the numerators and put the sum over the LCD = 17/36
- Simplify the fraction if possible. In this case it is not possible
@ pictures from various sites
They are either a multiple or a divisor.
-This is like a multiple, you have a pie. Your sharing it with your best friend. So, each of you get 1/2 of the pie. The 2 pieces of the pie are too big for you two to eat. So, you went and cut the 2 pieces into half. Now you both have 2/4.
-To find a multiple of a fraction, you multiply both the numerator and the denominator by the same number.
-Example: 2/4 x 5/5 = 10/20
-This is a divisor, you have a pie. It was cut into 4 pieces. You and your friend are going to share it. So, you get 2/4 and he gets 2/4. You put your 2 pieces together and realize you have 1/2 of the whole pie.
-To find a divisor of a fraction, divide both the numerator and denominator by the same number.
-Example: 50/60 divide by 10/10 = 5/6
How to convert a improper fraction to mixed
Step one: check how much the denominator can go into the numerator. Then put the whole number for the mixed as how many times the denominator can go into the numerator.
Step two:The remaining numbers are the numerator and the denominator stays the same.