How the hell do you add fractions!!!?

Question

I've spent like 1hr going through books, looking at websites and I just can't figure it out!!
I think I have the basic idea, ok let's say this is the question
3/4 + 7/8
Lcm = 8
Then what do you do?? Please put it in SIMPLE terms

How about actully telling me how to do it...

Answer 1

This is how you change 3/4:
Make 8 your denominator. ?/8.
What do you multiply 4 with to get 8? 2.
Multiply 3 with 2 as well. You get 6/8.
6/8 + 7/8 = 13/8. And you're done.

Answer 2

Lcm = 8 means that you need the denominator (the bottom) of both fractions to be 8. The first fraction is 3/4. To make the denominator 8, you need to multiply the current denominator (4) by 2. Whatever you do to the bottom, you have to do to the top. Multiply 3 (the numerator) by 2 to get 6 and 4 (the denominator) by 2 to get 8. The resulting fraction would be 6/8. If you simplify 6/8, you would get 3/4, wouldn't you? It's still the same fraction, but in a form that you can add to 7/8 with. Still with me? Your problem is now 6/8 + 7/8. Add the numerators. 6+7 = 13. Keep the denominators the same. Your resulting fraction is now 13/8. This is an improper fraction, meaning that the top is bigger than the bottom. You need to make it a mixed number. To make it a mixed number, first ask yourself 'how many times does 8 go into 13? The answer is one, so put your whole number as 1. 8 x 1 = 8, so do the problem 13 - 8 to get 5. Keep the denominator the same. The resulting fraction is 1 and 5/8, written as 1 5/8. Hope this helped because I spent a while on it.

Answer 3

The usual way of adding fractions is to find a common denominator. In this case it will be 8. Multiplying 3/4 by 2/2 gives you 6/8. It is then easy to add 6/8 + 7/8 which is 13/8.
The question is how do you know to multiply by 2/2?
You need a command of prime factors. For example, 4 has the prime factors 2,2 since 2 x 2 =4. 8 has the prime factors 2, 2, 2 since 2 x 2 x 2 = 8. This is not a good example to make the next point so let us add 3/4 and 2/10. The prime factors of 4 are 2, 2. The prime factors of 10 are 2, 5. The numbers that are in one or both of the prime factorizations are 2, 2, 5. Multiplying these together yield 2 x 2 x 5 = 20. This is the number that will give us the common denominator we need.
To get a denominator of 20 for 3/4 we multiply by 5/5 and get 15/20. Similarly 2/10 x 2/2 = 4/20
finally 15/20 + 4/20 = 19/20
You can find the numbers 5/5 and 2/2 by looking at the prime factors 2, 2, 5 which you found above. Obviously 4 needs to be multiplied by 5 to get 20 and 2 needs to be muliplied by 10 to get 20.
I can't get into more detail than this though some is needed. (Everything here keeps driving back to fundamentals. I don't know if you know how to find the union of two sets, or what that means. But that is what I am doing above with the two sets of prime numbers. What you don't know can hurt you.) One basic thing is that you have to know your prime numbers. They have applications all the way through your math studies. Knowing them and how to find the prime factors of any number will make your life easier and you better informed.

Now after all that. I presented it to you because that is the usual way it is taught. There is another. You can add fractions by performing three multiplicaions. You cross multiply for the numerator and multiply the denominators for the new denominator. For example:
3/4 + 2/10 = (3x10 + 4x2)/4x10 = 38/40 which reduces to 19/20
This will look better when we write it since we are not forced into printing single lines. I hope this helps and learn your primes and prime factorization!

P.S. Hell won't help you.

Answer 4

First find the lowest common denominator (LCD) for each fraction in the equation. (A trick that helped me remember which number is the numerator and which is the denominator is; the denominator is the number on the bottom of the fraction or Down; D starts the words Denominator and Down). Since you apparently know how to figure out how to find the LCD, you now just add the top two numbers (numerators) together. In your example 3/4 + 7/8 becomes 6/8 +7/8. Add the two top numbers (numerators) together and you get 15. The "Down" numbers (denominators) remain unchanged at "8". So your answer is 15/8. To reduce this fraction divide 8 into 15 and you get 1 with a remainder of 7 or 7/8. Put the 1 and the 7/8 together and your final answer is: 1 7/8.

Answer 5

Let us take the example given by you:

3/4 + 7/8

LCM is indeed 8 and then

(6/8 + 7/8) = 13/8 or 1 and 5/8

What did we do? We divided 8 by the denominator and used that number to multiply the numerator of the fraction. In the case of the first fraction, we have 8/4 = 2 and so we put 3 multiplied by 2 = 6 in the numerator. For the second fraction we have 8/8 = 1 and so the numerator 7 remains 7. Since the denominator is common now, 8, we can add the numerators and so we get 6 + 7 = 13.

Hope it is clear now.

Answer 6

Multiply top and bottom of first fraction by 2 to make it 8ths also.
This will make it 6 / 8 . Now add the top numbers 6 + 7 and use the common bottom number. 6 + 7 / 8 -- or 13 / 8

Another way to do this : Multiply the first and last numbers 3*8. Multiply the inner two numbers 4*7. Add 24 and 28, and put it over the product of the two bottom numbers 4*8 This will be 52 / 32. But this can be reduced by dividing both top and bottom by 4 to get 13 / 8

This second way, although longer and harder, will actually be easier if you have to add something like 1/5 and 5/6, where the common denominator is hard to find.
1*6 + 5*5 divided by 5*6 = 31 / 30

Answer 7

What you have to do is make the denominators the same number before you can add the top together. So if you multiply 3/4 by 4 and 7/8 by 2 you get 12/16 + 14/16 which = 26/16. Then all you have to do is simplify. Take out the largest number possible from both numbers (has to be the same number). In this case, take out a 2 to get an answer of 13/8.

Answer 8

Add only the numerators, the denominators must always be the same, for example:
2/7 + 4/7 = 6/7
(just add the numbers above the line or the"numerators". The denominators stay the same.

But when the "denominators"(the number under the line) are different, you must get the least common denominator(LCD) because before you could add, the denominators must be the same, like our example above. In your given example, take 3/4 & convert "4" to 8 to have the same denominator with 7/8, so how do you do this?multiply it by 2,still with me?and remember, whatever number you multiply with the denominator, you must also multiply with the numerator, so: 3/4 x 2/2=6/8.now you could add 6/8 with 7/8, which is equal to 13/8.

Answer 9

Haha, I Had trouble with these to.

3/4 + 7/8. First you find common denomaters.
Which, in this case, is 8. Because 4 goes into 8 twice, you times the bottom AND the top. ( what you do to the bottom, you do to the top.
So now you have 6/8 + 7/8. You can add straight across now.
13/8.
Thats an Improper fraction, if you want to change it, divide 8 into 13.
Which is 1 5/8 because 8 goes into 13 1 time, ( which is your whole number) and the remainer is 5,( your numerator) and then you kept your denomater.

Answer 10

LCM means least common multiple.

This is the smallest number that is divisible by both the numbers.

In the addition of two fractions, you need to take the LCM of the denominators.

The LCM of 4 and 8 is 8. 8 is divisible by both 4 and 8.

get both the denominators to the lcm by mutliplying the numerator and denominator with the same number.

3/4 + 7/8 = 3/4*2/2 + 7/8 *1/1

= 6/8 + 7/8

= (6 + 7)/8

= 13/8.

Answer 11

An easy way is to make denominators the same:-
6 / 8 + 7 / 8
= 13 / 8
= 1 5/8