Fast ten points!!! how do i find the common denominator when adding fractions?

Question

I have tried every way. I forgot how to do it.

eg: 4 1/2 tons + 1 1/6 + 1 3/4 =

9/2 + 7/6 + 7/4 = ? Did I do it right so far?

How do I get the common denominator. I am helping my son and I forgot. It's been so long. yikes.

Answer 1

One way (the fastest) to find the common denominator is to multiply the three denominators.  In this case 2x6x4 = 48.  But it isn't the lowest.  From here you can divide by 2 and see that 24 is also common to the three.  But you can also see that 12 is common to the three.

So in this example, it would be 54/12+14/12+21/12 which equals 89/12.  Divide this out, and you get 7 5/12 tons.

Answer 2

The lowest common denominator is the lowest number that all of the denominators divide into without a remainder.

You have denominators of 2, 6, and 4.  All 3 of these numbers go into 12 evenly.

So you would have 54/12 + 14/12 + 21/12

You can always multiply the denominators together to get a common denominator.  2 x 6 x 4 is 48, and just looking at the numbers tells you that you can find a smaller number.  6 x 4 is 24, and 2 also goes into 24.  But 6 x 2 is 12, and 4 goes into 12.  That's the lowest number that all 3 will go into without a remainder.

Answer 3

You figure what # will each of your current den. go into (12) then divide each into 12 and so on

Answer 4

Know your multiplication tables cold.  Calculators are no use for factoring.

What is the smallest number divisible by 2, 6, 4 ?

12

((9*6)/12) + ((7*2)/12) + ((7*3)/12) = ?

Remember now?

Answer 5

Yes you have it right so far.  Next you find the lowest number that all the denominators multiply to.  In this case it would be 12.  Get it?  Then you multiply the nmerator by what the original denominator was mulitplied by to get 12 ( you would multiply 9 by 6, 7 by 2, 7 by 3 ).  Then you add all the numerators together and 12 would be your denominator.  Then you change it to a mixed fraction.  The answer to this one would be 7 5/12.

Answer 6

You have to find a number that is a multiple of every denominator.  In this case it is 12.

Multiply BOTH the top and bottom of the first fraction by 6 to get 54/12.

Multiply BOTH the top and bottom of the second equation by 2 to get  14/12.

Multiply BOTH top and bottom of the third equation by 3 to get 21/12.

Finally add 54/12 + 14/12 + 21/12 = 90/12 or 7 1/2 or 7.5

Answer 7

common denom can be seen by

taking out common factors of denom

(2, 6, 4)

2(1, 3, 2)

now you see 2(1, 3, 2)

let the outside times the inside.

2x1x3x2

you get ur common denom.

12

hope i helped (:

Answer 8

You did it right so far... One way is to get the denominations do them 1 at a time...

you have 2,4, and 6 as your denominators.

the Lowest common multiple of 4 and 6 is 12, right, and 12 and 2's LCM is obviously 12.

Now convert:

9/2=54/12+14/12+21/12=89/12=7 5/12

Answer 9

Notice that 12 divides by 2, 6, and 4

(9/2)(6/6) + (7/6)(2/2) + (7/4)(3/3)

54/12 + 14/12 + 21/12 = 89/12

89 is a prime number so your final answer is 89/12 or 7 5/12

Answer 10

you have it right so far. the common denominator is 12.  the fraction would then be 54/12 + 14/12 + 21/12 = 89/12

Answer 11

I know how to do it, but i'm not sure if I can explain it well but I'll try. Anyway, you find the common denominator by determining what the lowest common multiple is of the two denominators. For example, 1/2 +  2/3= to 1 1/6. I got that by figuring out what the lowest common multiple is of 3 and 2, which is 6. In 1/2, I multiplied by 3/3 to get 3/6 simplified to 1/2. In 2/3, I multiplied by 2/2 which gives 4/6, simplified to 2/3. Therfore 4/6 + 3/6 is 7/6 simplified to 1 1/6. I hope I didn't confuse you! I hope I helped some. I haven't had a math class with fractions in over 20 years, so my explanation may be rusty!

Answer 12

4 = 8/2

Therefore   4 1/2 = 8/2 + 1/2 = 9/2

Is it the way that you want ?