Skip to navigation | Skip to content

Share your knowledge. Make a difference.

Math hints 1

1 - I can do better 2 - Jury's out 3 - Pretty darn good 4 - Splendiferous 5 - Awesometastic (by 1 person)   Your rating: 1 - I can do better 2 - Jury's out 3 - Pretty darn good 4 - Splendiferous 5 - Awesometastic

Ranked #3108 in How-To, #30983 overall

Rated G. (Control what you see)

Fractions

 

B"H

Fractions can be daunting for children and adults, but with a few hints, they become less mysterious.

Defining Fractions 

Fractions are just another way of doing division. Think of them in terms of a pie or a pizza that needs to be cut into enough pieces to feed a group.

In the picture at the right, you see there are 8 people sitting around a pie. If you cut that pie so that each one gets a piece equal to all the other pieces, each person will get 1/8 (one-eighth) of the pie. This means that one pie is divided into 8 pieces.

If you had two pies to feed the eight people, each one would get 2/8 (two-eighths) of the pie (two pies divided into 8 pieces total). Another way of saying 2/8 is 1/4 (one-fourth) because each pie will need to be cut into 4 pieces (two pies cut into a total of eight pieces means each pie will need to be cut into four pieces).

 

Another way of looking at fractions is that you have groups of items that need to be split evenly between members of a group. The example at the right shows 12 marbles. Let's assume that three people are dividing a bag of 12 marbles. Each one gets 1/3 (one-third) of the total -- the total (one) divided by 3 people. If you count out the number of marbles in 1/3, you will see that each third is equal to 4 marbles (4/12 -- four-twelfths -- is equal to 1/3).

If there are two people, but one person gets two shares, then that person would get 2/3 or 8 marbles. The whole (1) would be the same as all three thirds (3/3).

Arithmatic with Fractions 

How to add, subtract, multiply and divide fractions

In order to add fractions, you need to get the denominators (that is the bottom number of the fraction) of all the fractions to be added to be equal. Looking again at the pie example, we wouldn't know how to add 1/8 of the pie to 1/4 of the pie unless we remembered that 1/4 is the same as 2/8 (one divided by 4 is the same as 2 divided by 8). Then you could see that 1/4 of the pie (or 2/8) added to 1/8 is the same as adding 1+2 (see below):

1/4 + 1/8 = 2/8 + 1/8 = 1+2 /8 = 3/8

This is pretty easy when you are talking about fractions that have denominators (bottom number on a fraction) that are related to each other (like 4 and 8, 3 and 9, for example), but it's harder when the numbers aren't related (like 8 and 9, for example).

Keep in mind that any number divided by itself equals one. 3/3, 8/8, 16/16, 298/298 -- all are equal to 1.

So what do you do if you have two unrelated numbers? Let's take 5 and 6. You need to find a number that both numbers can be divided into. In the case of 5 and 6, that number would be 30 (5X6). So, if you were trying to add 3/5 and 5/6, you would need to put both fractions in terms of x/30.

To do this, you need to multiply. Multiplying fractions is relatively easy. If you have two fractions, say 5/9 X 3/7 -- you multiply the numerators (top numbers) and put that as the numerator on the new fractions and multiply the denominators and use that answer as the new denominator -- in the example, you would multiply 5X3 for 15 on top and 9X7 -- or 63 -- on the bottom so:

5/9 X 3/7 = 5X3 / 9X7 = 15/63

Now back to our addition example.

If we want to add 3/5 and 5/6, we have to write both fractions in terms of how many 30ths they would be -- to do that, multiply 3/5 X 6/6, and 5/6 X 5/5. So you end up with:

3/5 + 5/6 = 18/30 + 25/30 (3X6/5X6 + 5X5/6X5) = 18+25 /30 or 43/30

Let's do another example:

2/3 + 5/8 =

in order to add these two, we need to put both fractions in terms of 24ths (3X8=24), so....

2/3 + 5/8 = [2/3 X 8/8] + [5/8 X 3/3] = 16/24 + 15/24 = 16+15 /24 or 31/24

Try some of your own examples for practice on your own.

Subtracting and Dividing 

Subtracting is like adding; Dividing is like multiplying

One last thought about arithmetical operations on fractions: Subtraction is like addition and division is like multiplication. How? I'll explain.

With subtraction, as with addition, you need to get the fractions into a form where the denominators are the same. For example: Let's take 5/6 and 3/5 again.

5/6 - 3/5 = (5/6 X 5/5) - (3/5 X 6/6) = 25/30 - 18/30 = 25-18 /30 = 7/30

another example:

2/3 - 5/8 = [2/3 X 8/8] - [5/8 X 3/3] = 16/24 - 15/24 = 16-15 /24 or 1/24

Division is like multiplication except you need to "flip" the term after the division sign. For example:

3/4 divided by 6/5 = 3/4 X 5/6 = 15/24 or 5/8

To understand why this works, see the picture at the right -- this represents 5 / 5/6. This means that you are taking 5 bars (or, it means you are taking 5 cups of raisins and dividing it into 5/6 cup portions). As you can see, the bars are each divided into sixths. As you can see, you can get 6 portions of five-sixths. This is the same as if you multiply 5 X 6/5 (this is the same as 5/1 X 6/5 = 30/5 = 6/1 = 6).

I hope this has helped you understand fractions a little bit better. If you have any questions, you can either leave a comment below or you can e-mail the author at compugraphd@gmail.com

Check out my other squidoo lenses:
Strong Biblical Women
Strong Biblical Women 2
Why Be Vegetarian
Vegetarianism: Getting Started 1
Vegetarianism: Getting Started 2
Rosh Hashana
Quick Vegan Cooking
Creating new recipes from old
Strong Biblical Women Part 3
Hanuka
About the Jewish Calendar
Witches and Morality
Presidential Trivia Quiz
Christmas and the Jewish Single
Presidents1: George Washington

Check out my blogs:

Israel and it's Place in the World
Jewish Singles
Strong Jewish Women

New Amazon Voting (Plexo) 

Mastering Essential Math Skills: 20 Minutes a Day to Success, Book 2: Middle Grades/High School by Richard W. Fisher

Mastering Essential Math Skills: 20 Minutes a Day to Success, Book 2: Middle Grades/High School by Richard W. Fisher

Are your students algebra ready?*Requires Only 20 more...0 points

The Giant Encyclopedia of Math Activities: For Children 3 to 6 (Giant Encyclopedia)

The Giant Encyclopedia of Math Activities: For Children 3 to 6 (Giant Encyclopedia)

Over 600 math activities organized by curriculum a more...0 points

New Guestbook 

Evelyn_Saenz

What a great lens! 5 stars and Favored!
The Purple Gallinulesloved your lens so much that they are sending you some virtual Math Manipulatives to play with.

Posted May 01, 2008

New ShopIt 

Pink Knitted Outfit Teenage Doll

B"H Pink knitted outfit for teenage doll

$7.50

Buy now

Sold By: Compugraph_Designs

Knitted Teenage Doll Dress

B"H Pink on top, multi-colored on the bottom -- hand knitted dress

$10.00

Buy now

Sold By: Compugraph_Designs

Pink Velour Knitted Scarf

B"H Hand-knitted pink scarf. various colors mottled within the pink yarn.

$5.00

Buy now

Sold By: Compugraph_Designs

Silver Jewish Star Necklace

B"H This is an original design I created. Sterling Silver stylized Jewish star on a silver chain.

$60.00

Buy now

Sold By: Compugraph_Designs

Silver Chai Necklace

B"H This is an original design I created. Sterling Silver Chai (Hebrew for Life) on a silver chain.

$60.00

Buy now

Sold By: Compugraph_Designs

X
compugraphd

About compugraphd

B"H

Hi -- I'm a graphic artist from NJ. I have been designing since I was in High School (the margins of my notebooks have all sorts of pictures including jewelry designs, which is another of my vocations).

I also tutor math and other subjects, also since High School.

One of my favorite sayings (which rimes in Hebrew) -- "Al Ta'am V'Reah/Ein L'Hitvakeah" -- on taste and smell, there is nothing to argue about (or to each his or her own taste).

compugraphd's Pages

See all of compugraphd's pages