Thursday, January 26, 2012

Questions About How To Add Fractions With The Same Denominator

William asks…

Adding fractions with not the same denominator... please help?

4/15 - 1/12 = what???

Four over 15 minus One over tweleve. how do you find a common denominator and solve to get the answer. Please help thanks.

admin answers:

Fastest way 15*12 = 180

180 / 15 *4 = 48

180 / 12 *1 = 15

so its

48 / 180 - 15 / 180 = 33/180 or 11/60

Charles asks…

How do you add fractions with different denominators?

For example- the question is:

2/5 + 1/3

how would you go about converting them so they both have the same denominator? Please answer, desperately need to know.

admin answers:

You have to find a common denominator - thats the bottom number.
So, you've go 5 & 3. You know they both go into 15, so use 15.

5 goes into 15 three times - so you multiply the top # & bottom number by 3. 2x3=6, 5x3=15 that coverts to 6/15. Now for 1/3 - 3 goes into 15 five times, so multiply both #'s by 5. 1x5=5, 3x5=15, so that converts to 5/15. That give syou 6/15 + 5/15 equals 11/15!

George asks…

Adding and Subtracting Fractions-Questions on lesson plan needed?

Here is the problem. If you read through this what questions would you ask your instructor to futher explain. Thanks i have to write a detailed lesson plan and need 2 to 3 questions. Here is the problem



This will be the process of how to add and subtract fractions
Terms
denominator -- in a fraction notation, the denominator specifies the total number of equal parts. It is located on the bottom if the fraction is vertical or on the right if the fraction is set up horizontally.
numerator -- in a fraction notation, the numerator specifies how many parts you have. It is located on the top if the fraction is set up vertically or on the left if the fraction is set up horizontally.
proper fraction – Is an amount less than 1. In a proper fraction, the numerator is always less than the denominator.
improper fraction – Is a number with amount greater than or equal to 1. In an improper fraction, the numerator is either larger than or the same as the denominator
First the addition problem of adding fractions.

5/10 + 3/10=
Since the denominator is the same you keep the denominator the same so it comes straight across as /10
So then you take the 5 and the 3 and you add them
5+3=8
So the total would be put on top of the 10 to represent the numerator.
The answer would be 8/10
5/10+3/10=8/10
But this you can simplify more by dividing both top and bottom by the same number that goes into both.

We are going to use 2.
So take the 8 and divide it by 2
8/2 which is 4.
Then take the 10 and divide it by 2
10/2 which is 5
So the new answer would be simplified to 4/5
So final answer would be
5/10+3/10=8/10=4/5
Now for subtraction.

The problem is 4/5 – 1/2 =
Now since the denominator is different you will have to change them to the same. This is simply done by multiplying both to get a common number. Whatever you multiply the denominator in each fraction by you have to multiply the numerator by also.

So lets take 4/5 first
If we want to change the denominator to 10 a common for both fractions then we wil use 2.
4/5 would be done by multiplying 4 by 2
4*2=8
and 5 by 2
5*2-10
Making the fraction now 8/10

Now we will do the same with ½
To get 10 for this we have to multiply by 5.
The 1 first by 5
1*5=5
Then the 2
2*5=10
So that makes this fraction
5/10

Our problem now reads as
8/10-5/10=
as in addition you keep the denominator the same so the 10 stays put /10
To finish it off you subtract the 5 from the 8 to get the numerator.
8-5=3
So the answer would be 3/10
There is no simplifying needed here so the final answer would be
8/10-5/10=3/10

admin answers:

Honestly I wouldnt ask for much more explanation. I am very knowledgable with this math so I guess there's a sense of biasness there but I would give atleast 2 examples for each. Have 2 examples for add and sub with the same den. And have 2 examples of add and sub without the same den.

Math is one of those things that repetition is the key to success. When you show multiple examples it gives learners a more concrete idea on how the principles work. The more problems/examples the better. Also it doesn't hurt to play a small game with a few questions when you get done with your lesson. Have the class participate with the problems, allowing them person practice. You then can see first hand some common mistakes that may take place when working out these problems.

Good work!!

Betty asks…

Solving fractions?

I have no clue if I'm doing them right I need someone to give me steps on how to solve fractions, ones that are adding, subtraction, multiplication, and division problems.

like: 3/8 + 15/16

21/27 - 7/36

18/39 x 26/54

not the easy ones with the same denominator like 12/12 + 12/12 lol those I have down real good lol

admin answers:

You need to find the LCD (Least Common Denominator) That way you can just add the top numbers real easy.
So...
3/8 + 15/16 The LCD is 16
You have to multiply the first fractions denominator (bottom number) by 2 to get it to 16 and the second equation by 1 (Or staying the same) because it's already at 16.
When you multiply the denominator you also have to multiply the numerator (top number) by the same number.

3/8 would turn into 6/16
6/16 + 15/16 = 21/16

21/27 - 7/36 Gotta do some calculator testing but the LCD is 108
1st one will be multiplied by 4, and the 2nd by 3
84/108 - 21/108 = 63/108 and simplified 7/12

Sandy asks…

conversion of fractions to decimals?

when you convert fractions into decimals you multiply the denominator until it is a mutiple of 10, 100, or a 1000 or a number with and 0 then multiply the numerator by the same number, then add the decimal oplace is this correct?


so if it the fraction is 1/30 how do you do that? i need to show working so i can;t just use calculator

admin answers:

To convert a fraction to a decimal, simply divide the numerator by the denominator.
For example 3/10 as a decimal. 3 divided by 10 = 0.3.
4/5= 4 divided by 5 =0.8.

1/30 = 1 divided by 30 = 0.3333 recurring.

Hope this helps

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